Impact of Annual Operator and Institutional Volume
on Percutaneous Coronary Intervention Outcomes
A 5-Year United States Experience (2005–2009)
Apurva O. Badheka, MD*; Nileshkumar J. Patel, MD*; Peeyush Grover, MD*; Vikas Singh, MD*;
Nilay Patel, MD; Shilpkumar Arora, MD; Ankit Chothani, MD; Kathan Mehta, MD;
Abhishek Deshmukh, MD; Ghanshyambhai T. Savani, MD; Achint Patel, MD;
Sidakpal S. Panaich, MD; Neeraj Shah, MD; Ankit Rathod, MD; Michael Brown, MD;
Tamam Mohamad, MD; Frank V. Tamburrino, MD; Saibal Kar, MD; Raj Makkar, MD;
William W. O’Neill, MD; Eduardo De Marchena, MD; Theodore Schreiber, MD;
Cindy L. Grines, MD; Charanjit S. Rihal, MD; Mauricio G. Cohen, MD
Downloaded from http://circ.ahajournals.org/ by guest on June 16, 2017
Background—The relationship between operator or institutional volume and outcomes among patients undergoing
percutaneous coronary interventions (PCI) is unclear.
Methods and Results—Cross-sectional study based on the Healthcare Cost and Utilization Project’s Nationwide Inpatient
Sample between 2005 to 2009. Subjects were identified by International Classification of Diseases, 9th Revision, Clinical
Modification procedure code, 36.06 and 36.07. Annual operator and institutional volumes were calculated using unique
identification numbers and then divided into quartiles. Three-level hierarchical multivariate mixed models were created. The
primary outcome was in-hospital mortality; secondary outcome was a composite of in-hospital mortality and peri-procedural
complications. A total of 457 498 PCIs were identified representing a total of 2 243 209 PCIs performed in the United
States during the study period. In-hospital, all-cause mortality was 1.08%, and the overall complication rate was 7.10%.
The primary and secondary outcomes of procedures performed by operators in 4th [annual procedural volume; primary and
secondary outcomes] [>100; 0.59% and 5.51%], 3rd [45–100; 0.87% and 6.40%], and 2nd quartile [16–44; 1.15% and 7.75%]
were significantly less (P<0.001) when compared with those by operators in the 1st quartile [≤15; 1.68% and 10.91%].
Spline analysis also showed significant operator and institutional volume outcome relationship. Similarly operators in the
higher quartiles witnessed a significant reduction in length of hospital stay and cost of hospitalization (P<0.001).
Conclusions—Overall in-hospital mortality after PCI was low. An increase in operator and institutional volume of PCI was
found to be associated with a decrease in adverse outcomes, length of hospital stay, and cost of hospitalization. (Circulation.
2014;130:1392-1406.)
Key Words: complications ◼ in-hospital mortality ◼ length of stay ◼ percutaneous coronary intervention
T
he 2007 American College of Cardiology Foundation/
American Heart Association/Society for Cardiovascular
Angiography and Interventions (ACCF/AHA/SCAI) clinical
competence statement on cardiac interventional procedures1
and the 2011 percutaneous coronary intervention (PCI) guidelines recommend (Class IC) that PCIs should be performed
by operators with an annual volume (>75 procedures) at
high-volume centers (>400 procedures) with on-site cardiac
surgery.2 The last decade has observed a decline in number of
PCIs performed, and many interventional cardiologists have
experienced a drop in procedural volume.3,4 As a result, the
Editorial see p 1343
Clinical Perspective on p 1406
Continuing medical education (CME) credit is available for this article. Go to http://cme.ahajournals.org to take the quiz.
Received February 13, 2014; accepted August 4, 2014.
From Yale New Haven Medical Center, New Haven, CT (A.O.B.); Staten Island University Hospital, Staten Island, NY (N.J.P., N.S., F.V.T.); UMass
Memorial Medical Center, Worcester, MA (P.G.); University of Miami Miller School of Medicine, Miami, FL (V.S., G.T.S., E.D.M., M.G.C.); Saint Peter’s
University Hospital, New Brunswick, NJ (N.P.); Mount Sinai’s St Luke Roosevelt Hospital Center, New York, NY (S.A.); MedStar Washington Hospital
Center, Washington, DC (A.C.); UPMC Shadyside Hospital, Pittsburgh, PA (K.M.); University of Arkansas, Little Rock, AR (A.D.); Icahn School of
Medicine at Mount Sinai, New York, NY (A.P.); Detroit Medical Center, Detroit, MI (S.S.P., M.B., T.M., T.S., C.L.G.); Cedar–Sinai Medical Center, Los
Angeles, CA (A.R., S.K., R.M.); Henry Ford Hospital, Detroit, MI (W.W.O.); Mayo Clinic, Rochester, MN (C.S.R.).
Parts of these data were presented at Society for Cardiovascular Angiography and Intervention 2014 Scientific Sessions. Abstract was selected among
the top 3 best of the best abstracts award competition.
*Drs Badheka, Patel, Grover, and Singh contributed equally to this work.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.
114.009281/-/DC1.
Correspondence to Apurva Badheka, MD, Yale New Haven Medical Center, 333 Cedar St, New Haven, CT 06520. E-mail [email protected]
© 2014 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.114.009281
1392
Badheka et al Percutaneous Coronary Intervention 1393
2013 ACCF/AHA/SCAI clinical competence statement now
recommends a minimum requirement of 50 coronary interventional procedures per year (averaged over a 2-year period) to
perform PCIs.5 These recommendations, however, are based
on expert opinion derived from the interpretation of data from
multiple sources with inherent limitations. Some of these data
were derived from state registries and are dated.5–24
The purpose of this study was to determine the association
of annual PCI operator and institutional volume with in-hospital mortality, peri-procedural complications, length of hospital stay, and cost of hospitalization using the nation’s largest
available all-payer insurance inpatient database in a recent era
(2005–2009) during which procedural techniques and practices have remained relatively stable.
Methods
Data Source
Downloaded from http://circ.ahajournals.org/ by guest on June 16, 2017
We analyzed 5-year data from the 2005 to 2009 from National
Inpatient Sample (NIS) database. The NIS is a subset of the Healthcare
Cost and Utilization Project sponsored by the Agency for Healthcare
Research and Quality (AHRQ). The NIS is the largest publicly available all-payer inpatient care database in the United States; including
data on approximately 7 to 8 million discharges per year, it is stratified to sample approximately 20% sample of US community (nonfederal, short-term, general, and specialty) hospitals. National estimates
are produced using sampling weights provided by the sponsor. The
NIS data have been used previously to study trends and predictors of
healthcare usage, patterns of major procedures, access and disparity
of care, procedural adverse effects, hospitalization trends, cost, quality, and outcomes.25,26 Each individual hospitalization is deidentified
and maintained in the NIS as a unique entry with 1 primary discharge
diagnosis and ≤ 24 secondary diagnoses during that hospitalization.
Each entry also carries information on demographics.
Annual data quality assessments of the Nationwide Inpatient
Sample are performed, to maintain the internal validity of the database. Furthermore, comparisons against the following data sources
strengthen the external validity of the Nationwide Inpatient Sample:
the American Hospital Association Annual Survey Database, the
National Hospital Discharge Survey from the National Center for
Health Statistics, and the MedPAR inpatient data from the Centers
for Medicare and Medicaid Services.27–29
Study Design and Patients
This was a cross sectional study using the NIS database between the
years 2005 to 2009. Ascertainment of all diagnoses and procedures
was made by using the International Classification of Diseases, 9th
Revision, Clinical Modification (ICD-9-CM) codes. PCI with stent
placement was identified by procedure codes 36.06 (non–drug-eluting
coronary artery stents) or 36.07 (drug-eluting coronary artery stents)
in any of the procedural fields.27 To restrict our evaluation to the use
of PCI in a typical adult population, only participants aged ≥18 years
were included (n = 839 923). We excluded all observations with a
missing unique operator identifying number (n= 382 385), missing
data for age (n=15), sex (n=14), length of stay (n=1), and mortality
during hospitalization (n=10). The final study sample consisted of
457 498 procedures (Figure 1). This study involved deidentified data
and was therefore exempted from institutional review board.
Outcomes
The primary outcome was in-hospital all-cause mortality, and the
secondary outcome was a composite of in-hospital mortality and
peri-procedural complications. Preventable procedural complications
were identified by Patient Safety Indicators (PSIs), which have been
established by the AHRQ to monitor preventable adverse events during hospitalization. These indicators are based on ICD-9-CM codes
Figure 1. Study design and patients selection. NIS indicates
National Inpatient Sample database.
and Medicare severity Diagnosis-Related Groups, and each PSI has
specific inclusion and exclusion criteria.30 PSI individual technical
specifications were used to identify and define preventable procedural
complications (viz postprocedure respiratory failure, postprocedure
physiological and metabolic derangement with acute renal failure
requiring dialysis, postprocedure pulmonary embolism or deep vein
thrombosis, procedural infectious complications including postprocedure sepsis and central venous catheter related bloodstream infection,
and accidental puncture or laceration).
Other procedure related complications including hemorrhage
requiring blood transfusion, iatrogenic cardiac complications, pericardial complications, coronary artery bypass graft, procedural
stroke or transient ischemic attack, and vascular complications were
identified using ICD-9-CM codes (Table I in the online-only Data
Supplement) in any secondary diagnosis field. To prevent classification of a preexisting condition (eg, stroke or heart block) as a complication, cases with the ICD-9-CM code for a complication listed as
the principal diagnosis (DX1) were excluded. Vascular complications
were defined as PSI code for accidental puncture or ICD-9-CM codes
for injury to blood vessels, creation of arteriovenous fistula, injury
to the retroperitoneum, vascular complications requiring surgery, and
other vascular complications not elsewhere classified. “Any complication” was defined as occurrence of one or more procedural complications listed in Table I in the online-only Data Supplement).This
methodology has been used in previous studies.31
Other outcomes studied were the length of stay and cost of hospitalization. Length of stay includes both observational status and inpatient admissions. Disposition was classified into 3 categories: those
who were discharged home or with home care services were classified as home-based discharge, those who were discharged to short- or
long-term nursing home or transferred to another facility were classified as discharge to another facility, and those who died in-hospital
were classified as in-hospital mortality.
To calculate estimated cost of hospitalization the NIS data were
merged with cost-to-charge ratios available from the Healthcare Cost
and Utilization Project. We estimated the cost of each inpatient stay
by multiplying the total hospital charge with cost-to-charge ratios.
Adjusted cost for each year was calculated in terms of the 2010 cost,
after adjusting for inflation according to the latest consumer price
index (CPI) data released by US government on January 16, 2013.32
By doing this we standardized costs over the study period.
1394 Circulation October 14, 2014
Table 1. Baseline Characteristics of the Study Population, According to Quartiles of Annual Operator Volume
1st Quartile
(≤15)
2nd Quartile
(16–44)
3rd Quartile
(45–100)
4th Quartile
(>100)
457 498
115I813
(25.31%)
115 373
(25.22%)
112 301
(24.55%)
114 011
(24.92%)
2 243 209
560 802
560 803
560 802
560 802
64.59±0.04
63.87±0.04
64.53±0.04
65.27±0.04
Overall
PCI unweighted No.*
PCI weighted No.†
P
Value
Patient characteristics
Age, mean±SE
64.56±0.02
Sex, %
<0.001
<0.001
Male
66.21
63.93
67.45
67.48
66.03
Female
33.79
36.07
32.55
32.52
33.97
Race,‡ %
<0.001
White
69.69
67.39
69.34
70.73
71.38
Non-white
16.88
20.47
17.12
13.99
15.8
Comorbidities, %
Charlson comorbidity index§
<0.001
Downloaded from http://circ.ahajournals.org/ by guest on June 16, 2017
0
25.17
18.11
23.89
28.53
30.37
1
39.71
37.47
41.26
40.88
39.29
≥2
35.12
44.43
34.85
30.59
30.34
<0.001
History of obesity
10.53
11.84
10.84
9.91
9.5
<0.001
History of hypertension
68.78
68.6
67
67.52
71.99
<0.001
History of diabetes mellitus
31.58
33.74
30.32
29.79
32.42
<0.001
0.68
1.89
0.46
0.2
0.15
<0.001
17.91
13.86
12.89
13.65
<0.001
History of congestive heart failure
History of chronic pulmonary disease
14.6
Peripheral vascular disease
10.13
9.86
9.48
10.31
10.89
<0.001
Fluid-electrolyte abnormalities
or renal failure
13.19
20.19
12.64
9.83
9.89
<0.001
<0.001
Neurological disorder or paralysis
2.92
3.99
2.87
2.36
2.44
Anemia or coagulopathy
6.83
10.56
6.86
4.91
4.86
<0.001
Hematologic/oncological malignancy
1.34
1.77
1.3
1.14
1.13
<0.001
Weight loss
0.2
1.01
0.39
0.21
0.2
<0.001
Rheumatoid arthritis/other
collagen vascular disease
1.53
1.92
1.52
1.44
1.23
<0.001
History of valvular disorder
0.22
0.63
0.14
0.07
0.05
<0.001
Depression, psychosis/substance abuse
6.24
8.36
6.19
5.11
5.21
<0.001
Median household income category for patient’s zip code,¶ %
<0.001
0–25th percentile
26.9
26.58
26.67
25.92
28.42
26–50th percentile
25.89
24.94
26.13
27.07
25.46
51–75th percentile
23.03
23.84
24.36
23.37
20.54
76–100th percentile
21.73
22.21
20.33
21.11
23.25
Medicare/Medicaid
55.16
55.2
53.12
55.61
60.5
Private, including HMO
36.07
35.34
37.8
37.06
34.1
7.66
9.1
Primary payer, %
Self pay/no charge/other
<0.001
8.96
7.21
5.33
Hospital characteristics
Hospital bed size, %║
Small
<0.001
6.25
5.35
5.29
6.95
7.46
Medium
19.64
21.32
19.25
19.38
18.57
Large
73.66
72.81
74.54
73.39
73.89
Hospital location, %
Rural
<0.001
5.03
4.41
5.3
6.21
4.22
(Continued)
Badheka et al Percutaneous Coronary Intervention 1395
Table 1. Continued
Overall
1st Quartile
(≤15)
94.52
95.07
93.78
93.51
95.7
Northeast
24.64
20.41
18.75
24.51
35.04
Midwest/North Central
15.68
15.77
16.28
15.86
14.82
South
47.74
48.81
50.22
48.07
43.81
West
11.94
15
14.75
11.57
6.33
Urban
2nd Quartile
(16–44)
3rd Quartile
(45–100)
4th Quartile
(>100)
Hospital region, %
<0.001
Hospital teaching status, %
<0.001
Nonteaching
43.9
47.99
45.66
40.5
41.27
Teaching
55.65
51.49
53.42
59.22
58.65
Emergent admission
67
82.28
68.69
61.12
55.44
Elective admission
32.59
17.27
30.8
38.53
44.23
Weekdays
86.94
80.14
85.29
89.82
92.73
Weekend
13.06
19.86
14.71
10.18
7.27
Admission types, %
<0.001
Admission day, %
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Length of stay, mean±SE
Total adjusted cost in dollars, mean±SE
P
Value
<0.001
2.81±0.05
4.12±0.01
2.83±0.01
2.28±0.01
2.01±0.01
<0.001
17 894±17$
21 111±44$
17 997±33$
16 669±31$
15 783±29$
<0.001
Disposition, %
<0.001
95.24
91.88
95.39
96.68
97.1
Facility/others
3.4
6.06
3.12
2.22
2.1
AMA
0.28
0.37
0.34
0.22
0.2
Single vessel single stent
39.73
41.57
40.93
37.93
38.4
Single vessel more than 1 stent.
16.32
16.1
16.93
Home
Vessels involved, %
Bifurcation stenting
Multivessel PCI
Use of assist devise or IABP, %
Shock, %
<0.001
16.23
16.04
1.3
1.28
1.32
1.32
1.3
42.64
41.05
41.53
44.71
43.37
2.21
2.76
2.49
1.88
1.71
1.9
2.75
2.23
1.52
1.09
36.45
46.53
41.29
33.13
24.54
Fractional flow reserve, %
0.12
0.13
0.13
0.1
0.12
Intravascular ultrasound, %
4.67
4.25
4.46
4.64
5.33
AMI, %
<0.001
Frequencies (%) in the columns may not sum to 100% to account for missing data. AMA indicates against medical advice; AMI, acute myocardial infarction; HMO,
health maintenance organization; IABP, intra-aortic balloon pump; PCI, percutaneous coronary intervention; and SE, standard error.
*No. of unweighted PCI.
†No. of weighted PCI.
‡Race was missing in 13.4% of the study population.
§Charlson/Deyo comorbidity index was calculated as per Deyo classification.
¶This represents a quartile classification of the estimated median household income of residents in the patient’s ZIP Code. These values are derived from ZIP Codedemographic data obtained from Claritas. The quartiles are identified by values of 1 to 4, indicating the poorest to wealthiest populations. Because these estimates are
updated annually, the value ranges vary by year. http://www.hcupus.ahrq.gov/db/vars/zipinc_qrtl/nisnote.jsp
║The bed size cutoff points divided into small, medium, and large have been done so that approximately one-third of the hospitals in a given region, location, and
teaching status combination would fall within each bed size category. State and County QuickFacts. Washington, DC: US Census Bureau; 2012.
Annual Institutional and Operator
Procedure Volume
Annual institutional volume was determined using the unique
hospital identification number to calculate the total number of
procedures performed by a particular institution in a given year.
Similarly annual operator volume was computed using operator
identification number. The operator identification numbers in NIS
do not correlate across years, and hence the same operator performing the procedure in different years may be recorded under a
different identifier, but within the same year the operator identifiers
do not change. For the above reason, annual operator volume was
calculated on a year to year basis by matching the operator identification number related to a particular procedure to the total number
of procedures recorded under that operator identification number
in the given year.
The relationship between institutional and operator volume and
outcomes was represented as a nonlinear polynomial function using
restricted cubic spline transformations of the volume measure. The use
of splines is an established method to determine whether nonlinearity exists between a continuous variable and a dependent outcome by
using all data points to estimate the shape of an association between
1396 Circulation October 14, 2014
Table 2. Baseline Characteristics of the Study Population, According to Quartiles of Annual Institutional Volume
1st Quartile
(<=542)
2nd Quartile
(543 – 914)
3rd Quartile
(917 – 1641)
4th Quartile
(>1641)
457 498
114 569
(25.04%)
114 513
(25.03%)
114 172
(24.96%)
114 244
(24.97%)
2 243 014
569 426
(25.39%)
551 262
(24.58%)
562 313
(25.07%)
560 012
(24.97%)
63.67±0.04
64.60±0.04
64.84±0.04
65.18±0.04
Demographic Variable
Overall
PCI unweighted No.*
PCI weighted No.†
P Value
Patient characteristics
Age, mean±SE
64.56±0.01
Sex, %
<0.001
<0.001
Male
66.21
66.37
66.04
66.15
66.26
Female
33.79
33.63
33.96
33.85
33.74
White
69.69
67.41
68.61
76.20
66.54
Non-white
16.88
18.93
13.97
17.98
16.56
0
25.17
20.53
25.88
24.87
29.49
1
39.71
41.15
39.52
39.82
38.31
≥2
35.12
38.32
34.59
35.31
32.20
History of hypertension
68.78
65.55
66.82
71.93
70.83
<0.001
History of diabetes mellitus
31.58
30.42
30.47
32.92
32.51
<0.001
0.68
0.96
0.74
0.64
0.40
<0.001
History of chronic pulmonary disease
14.60
14.96
14.73
14.80
13.91
<0.001
Peripheral vascular disease
10.13
9.19
10.11
11.93
9.29
<0.001
Fluid-electrolyte abnormalities and/or renal failure
13.19
14.50
13.29
13.38
11.56
<0.001
Neurological disorder/paralysis
2.92
3.25
2.91
2.88
2.63
<0.001
Anemia/coagulopathy
6.83
7.58
7.06
6.80
5.86
<0.001
Hematologic/oncological malignancy
1.34
1.46
1.37
1.31
1.22
<0.001
Weight loss
0.46
0.64
0.49
0.41
0.30
<0.001
Rheumatoid arthritis/other collagen vascular disease
1.53
1.71
1.61
1.48
1.33
<0.001
History of Valvular disorder
0.22
0.28
0.24
0.22
0.15
<0.001
Depression, psychosis/substance abuse
6.24
7.05
5.98
6.23
5.66
<0.001
0–25th percentile
26.90
29.85
27.60
27.27
22.83
26–50th percentile
25.89
27.57
26.87
26.50
22.60
51–75th percentile
23.03
22.48
25.35
22.68
21.68
76–100th percentile
21.73
17.10
17.72
21.05
31.05
Race,‡ %
<0.001
Comorbidities,§ %
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Charlson comorbidity index¶
History of congestive heart failure
<0.001
Median household income category for patient’s zip code,║ %
<0.001
Primary payer, %
<0.001
Medicare/Medicaid
56.15
52.74
55.18
58.55
58.17
Private, including HMO
36.07
36.48
36.58
34.69
36.54
7.66
10.62
8.14
6.65
5.20
6.25
7.82
6.97
5.05
5.16
Medium
19.64
30.59
16.32
12.91
18.53
Large
73.66
60.51
76.71
81.32
76.31
Rural
5.03
12.63
4.15
3.19
0.00
Urban
94.52
86.30
95.85
96.09
100.00
Self pay/no charge/other
Hospital characteristics
Hospital bed size,# %
Small
<0.001
Hospital location, %
Hospital region, %
<0.001
<0.001
(Continued)
Badheka et al Percutaneous Coronary Intervention 1397
Table 2. Continued
Demographic Variable
Overall
1st Quartile
(<=542)
2nd Quartile
(543 – 914)
3rd Quartile
(917 – 1641)
4th Quartile
(>1641)
Northeast
24.64
12.65
10.55
38.91
36.37
Midwest or North Central
15.68
20.48
19.13
12.76
10.34
South
47.74
48.96
47.50
42.49
51.99
West
11.94
17.90
22.82
5.84
1.30
Nonteaching
43.90
61.08
60.60
31.84
22.09
Teaching
55.65
37.85
39.40
67.44
77.91
Emergent admission
67.27
71.63
63.56
69.53
64.23
Elective admission
32.73
28.37
36.44
30.47
35.77
Hospital teaching status, %
<0.001
Admission types, %
<0.001
Admission day, %
<0.001
Weekdays
86.94
82.50
86.15
88.27
Weekend
13.06
17.50
13.85
11.73
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Length of stay, mean±SE
Total adjusted cost, mean±SE
2.82±0.01
17894±15
3.22±0.01
2.84±0.01
2.75±0.01
90.90
9.10
2.47±0.01
19609±35
17774±35
17404±35
12355±35
95.24
93.68
95.24
95.75
96.29
Facility/others
3.40
4.39
3.30
3.04
2.84
AMA
0.28
0.37
0.31
0.27
0.19
Disposition, %
Home
P Value
<0.001
<0.001
<0.001
Vessels involved, %
<0.001
Single vessel single stent
57.2
60.27
58.66
56.98
53.36
Single vessel more than 1 stent.
20.56
20.01
19.46
20.23
22.33
1.88
1.87
1.71
2.28
1.64
20.35
17.85
20.16
20.52
22.67
1.90
2.78
1.97
1.63
1.22
<0.001
36.45
47.57
37.16
33.53
27.40
<0.001
Fractional flow reserve, %
0.12
0.14
0.24
0.07
0.04
<0.001
Intravascular ultrasound, %
4.67
4.69
3.68
4.56
5.72
<0.001
Bifurcation Stenting
Multivessel PCI
Shock, %
AMI, %
Frequencies (%) in the columns may not sum to 100% to account for missing data. AMA indicates against medical advice; AMI, acute myocardial infarction; HMO,
health maintenance organization; IABP, intra-aortic balloon pump; PCI, percutaneous coronary intervention; and SE, standard error.
*No. of unweighted PCI.
†No. of weighted PCI.
‡Race was missing in 13.4% of the study population.
§Variables are Agency for Healthcare Research and Quality comorbidity measures.
¶Charlson/Deyo comorbidity index was calculated as per Deyo classification.
║This represents a quartile classification of the estimated median household income of residents in the patient’s ZIP Code. These values are derived from ZIP Codedemographic data obtained from Claritas. The quartiles are identified by values of 1 to 4, indicating the poorest to wealthiest populations. Because these estimates are
updated annually, the value ranges vary by year. http://www.hcupus.ahrq.gov/db/vars/zipinc_qrtl/nisnote.jsp
#The bed size cutoff points divided into small, medium, and large have been done so that approximately one-third of the hospitals in a given region, location, and
teaching status combination would fall within each bed size category. State and County QuickFacts. Washington, DC: US Census Bureau; 2012.
an exposure (operator volume) and an outcome.33 To make them clinically relevant and for the ease of interpretation, annual institutional
and operator procedure volume were also divided into quartiles.
Baseline characteristics of the study population that were studied for potential confounding assessment included patient and
hospital level characteristics. Patient level characteristics such
as age, sex, race, comorbid conditions using Deyo modification
of Charlson comorbidity index (CCI), median household income
according to ZIP Code, primary payer, admission type (urgent/
emergent versus elective), day of the admission (weekdays versus
weekend), and hospital level characteristics such as hospital location (urban/rural), hospital bed size (small, medium, and large),
region (Northeast, Midwest or North Central, South, and West),
teaching status, and annual institutional volume quartiles were
studied. Length of stay and cost of the hospitalization were also
studied.
We defined severity of comorbid conditions using Deyo modification of CCI (Table II in the online-only Data Supplement). This index
contains 17 comorbid conditions with differential weights. The score
ranges from 0 to 33, with higher scores corresponding to greater burden of comorbid diseases.34
Statistical Analysis
Stata IC 11.0 (Stata-Corp, College Station, TX) and SAS 9.3 (SAS
Institute Inc, Cary, NC) were used for analyses, which accounted for the
complex survey design and clustering. We stratified our study sample
by quartiles of annual operator volume (≤15, 16–44, 45–100, >101).
1398 Circulation October 14, 2014
Table 3. Adverse Clinical Events* Related to Percutaneous
Coronary Intervention by ICD-9 Code, 2005 Through 2009
Complications
Percentage
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Death
1.08
Any complications
7.10
Death + Any complications
7.70
Death + Vascular + Stroke + Cardiac+ Requirement
of open heart surgery
5.53
Death + Vascular + Stroke + Cardiac + Requirement
of open heart surgery + Renal + DVT + Infectious
6.35
Vascular complications
2.01
Postop-hemorrhage requiring transfusion†
0.50
Vascular injury
1.56
Cardiac complications
1.76
Iatrogenic cardiac complications
1.69
Pericardial complications
0.10
Requiring CABG
0.10
Respiratory complications (Post-op resp failure)
1.50
Postop-stroke/TIA
0.99
Renal and metabolic complications
Acute renal failure requiring dialysis
0.20
<0.1
Acute severe metabolic derangement
0.16
Postoperative DVT/PE
0.41
Postoperative infectious complications§
0.61
CABG indicates coronary artery bypass grafting; DVT, deep venous
thrombosis; PE, pulmonary embolism; and TIA, transient ischemic attack.
*Details in Table II in the online-only Data Supplement.
†Hemorrhage requiring transfusion was identified as any patient having
postoperative hemorrhage and also received transfusion.
‡Infectious complications were identified as composite of postoperative
sepsis, septic shock, or catheter-related infection.
All analyses were performed using the designated weighting specified
in the data set to minimize biases. Differences in baseline characteristics were examined using 1-way analysis of variance for continuous
variables (reported as mean±SD) and χ2 test for categorical variables
(reported as %). P value of less than 0.05 was considered significant.
Hierarchical Modeling
Hierarchical mixed effects models were generated to identify the
independent multivariate predictors of the primary and secondary
outcomes. Hierarchical modeling is designed to analyze data with
nested observations and more appropriate to simple regression modeling for an available dataset. The NIS dataset is inherently hierarchical
(viz the data has group- [ie, hospital] specific attributes and within each
group there are patients which contribute patient-specific attributes
to the data). Hierarchical models take into consideration the effect
of nesting. Three-level hierarchical models (with patient level factors
nested within hospital level factors) were created with the unique hospital identification number and hospital region incorporated as random
effects within the model (meaning that patients treated at the same hospital may experience similar outcomes as a result of other processes
of care).
We excluded race from the multivariable models because nearly
13.42% of the observations were missing. Because 94.52% of these
procedures were performed in urban hospitals, we did not include rural/
urban location of hospital in the model. In all multivariate models, we
included hospital level variables like annual institutional volume, hospital region (Northeast, South, Midwest with West as referent), teaching
versus nonteaching hospital, and patient-level variables like age, sex,
Deyo modification of CCI, myocardial infarction, shock, emergent/
urgent versus elective admission, admission over the weekend, median
household income, primary payer (with Medicare/Medicaid considered
as referent; Table III in the online-only Data Supplement), in addition
to annual operator procedure volume. All interactions were thoroughly
tested. Colinearity was assessed using variance inflation factor.
Model discrimination was assessed using the c-index (Table IV
in the online-only Data Supplement). The probability of death was
calculated for each patient using the full hierarchical model. Average
adjusted probability of death was then calculated for each level of
institutional and operator volume. The absolute risk reduction between
each level of institutional and operator volume was the absolute difference in average probability of death in each group, which represents
possible change in patient mortality risk associated with changing the
level of institutional and operator volume for the average patient, after
adjusting for all potential confounders as described above.
Subgroups analyses were carried out in Charlson ≥2, emergent
admission, myocardial infarction and or shock, and multivessel subgroups. To compare current guideline with previous, we also divided
operator volume into 3 groups: ≤50 PCIs/yr, 51 to 75 PCIs/yr, and >75
PCIs/yr. Length of stay and cost of care were not normally distributed
in the population and so were converted into logarithmic scale.
Results
Our analysis included 457 498 of an estimated total of
2 243 209 PCI procedures performed in the United States during the study period. The mean age of the study population was
64.56±0.02 years; 66.21% were male and 69.69% were white.
Most of the PCIs were performed in urban hospitals (94.52%),
during weekdays (86.94%), in an urgent or emergent setting
Figure 2. Median operator volume from 2005 to 2009.
Badheka et al Percutaneous Coronary Intervention 1399
Figure 3. Median institutional volume from 2005
to 2009.
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(67.00%). The primary expected payer was Medicare/Medicaid
(55.16%). Baseline characteristics of the study population are
shown in Tables 1 and 2. Given the large number of procedures
used for the analysis, most of the variables were statistically
different across operator volume quartiles.
Overall mortality and complication rates were 1.08% and
7.10%, respectively. Vascular complications were reported
at 2.01% with vascular injury accounting for 1.56% of total
complications. Other frequent complications included iatrogenic cardiac complications (1.69%), postoperative respiratory failure (1.50%), postoperative stroke (0.99%), and acute
renal failure requiring dialysis (<0.1%; Table 3).
Median operator PCI volume declined from 53 (2005) to 33
annually (2009; Figure 2). Median institutional PCI volume also
declined from 1024 (2005) to 693 annually (2009; Figure 3).
Annual Operator Volume and Outcomes
Crude cumulative mortality and complication rates decreased
significantly with increasing quartiles of operator volume
(Figure 4). Crude mortality rates were 1.68%, 1.15%, 0.87%,
and 0.59% in 1st (≤15 PCIs/yr), 2nd (16–44 PCIs/yr), 3rd
(45–100 PCIs/yr), and 4th (>100 PCIs/yr) quartile of operator volume, respectively. Similarly complication rates were
10.12%, 7.17%, 5.96%, and 5.19% with increasing quartiles
of operator volume. The association between operator volume
quartile and primary and secondary outcomes persisted even
after adjusting for potential confounding factors. Compared
with patients treated by lowest quartile of operator volume,
adjusted odds ratios of mortality for the patients treated by 2nd,
3rd, and 4th quartile of operator volume were 0.80 (0.74–0.87,
P<0.001), 0.81(0.74–0.89, P<0.001), and 0.65(0.58–0.73,
P<0.001), respectively (Table 4). Similarly adjusted odds
ratios for secondary outcome for the patient treated by 2nd,
3rd, and 4th quartile of operator volume were 0.75 (0.73–0.78,
<0.001), 0.67 (0.64–0.69, P<0.001), and 0.61 (0.58–0.63,
P<0.001) respectively, as compared with patient treated by
lowest quartile of operator volume.
Spline relationship between operator volume and primary
and secondary outcomes is demonstrated in Figure 5. Predicted
probability of mortality dropped with increasing operator volume and flattened at ≈300 procedures per year (Figure 5A).
A similar relationship was also found between the secondary
outcome and annual operator volume (Figure 5B).
The magnitude of change in risk-adjusted rate of mortality
with the change in operator volume is represented in Tables 5
and 6. Adjusted risk of mortality in a group of patients treated
by an operator performing ≤50 procedures/yr, 50 to 75 procedures/yr, >75 procedures/yr were 1.31%, 0.78%, and 0.54%,
respectively (Table 6). Similarly, adjusted risk of secondary outcome in a group of patients treated by an operator
performing ≤50 procedures/yr, 50 to 75 procedures/yr, >75
procedures/yr were 9.15%, 6.41%, and 5.73%, respectively
(Table 6).
Annual Institutional Volume and Outcomes
Figure 4. Crude mortality rate and complication rate according to
quartiles of operator volume.
Crude cumulative mortality and complication rates decreased
significantly with increasing quartiles of institutional volume
(Figure 6). Crude mortality rates were 1.54%, 1.15%, 0.94%,
and 0.68% in 1st, 2nd, 3rd, and 4th quartile of institutional volume,
respectively. Similarly complication rates were 8.06%, 7.07%,
7.29%, and 6.09% with increasing quartiles of institutional
volume. The association between institutional volume quartile and primary and secondary outcomes persisted even after
adjusting for clinical variables (Table III in the online-only Data
Supplement). However, the relationship between institutional
1400 Circulation October 14, 2014
Table 4. Multivariate Predictors of Primary and Secondary Outcomes
Primary
Outcome
OR (95% CI)
Secondary
Outcome
P Value
OR (95% CI)
P Value
Age (10-yr increment)
1.60 (1.55–1.65)
<0.001
1.11 (1.10–1.13)
<0.001
Female
1.20 (1.13–1.28)
<0.001
1.27 (1.24–1.30)
<0.001
Shock
14.49 (13.28–15.80)
<0.001
7.67 (7.25–8.11)
<0.001
Myocardial infarction
3.96 (3.58–4.39)
<0.001
1.74 (1.69–1.79)
<0.001
Charlson score*
0
Referent
Referent
1
2.33 (1.86–2.92)
<0.001
1.46 (1.40 - 1.53)
<0.001
≥2
3.61 (2.89–4.51)
<0.001
2.77 (2.65 - 2.89)
<0.001
0.817
1.00 (0.97–1.04)
Median household income
1st quartile
2nd quartile
Referent
0.99 (0.91–1.08)
Referent
0.904
3 quartile
1.00 (0.91–1.10)
0.991
1.02 (0.98–1.05)
0.405
4th quartile
0.92 (0.83–1.02)
0.126
0.98 (0.94–1.02)
0.362
rd
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Primary payer
Medicare/Medicaid
Referent
Referent
Private including HMO
0.77 (0.70–0.85)
<0.001
0.78 (0.76–0.81)
<0.001
Self pay/no charge/other
1.23 (1.08–1.40)
0.002
0.82 (0.78–0.87)
<0.001
Teaching vs nonteaching hospital
1.00 (0.91–1.11)
0.985
1.03 (0.98–1.09)
0.266
Weekend vs weekdays admission
1.06 (0.98–1.14)
0.162
1.00 (0.97–1.03)
0.921
Emergent/urgent vs. elective admission
1.43 (1.29–1.59)
<0.001
1.00 (0.97–1.03)
0.946
Use of assist devise or IABP
3.42 (3.11–3.75)
<0.001
2.69 (2.54–2.85)
<0.001
Annual institutional volume
1st Quartile (≤542)
Referent
Referent
2 Quartile (543–914)
0.95 (0.85–1.06)
0.362
0.98 (0.92–1.04)
3rd Quartile (917–1641)
0.89 (0.78–1.02)
0.099
1.06 (0.99–1.14)
0.088
4th Quartile (>1641)
0.88 (0.75–1.04)
0.137
1.02 (0.93 –1.12)
0.650
nd
0.461
Annual operator volume
1st Quartile (1–15)
Referent
Referent
2nd Quartile (16–44)
0.80 (0.74–0.87)
<0.001
0.75 (0.73–0.78)
3rd Quartile (45–100)
0.81 (0.74–0.89)
<0.001
0.67 (0.64–0.69)
<0.001
4th Quartile (>100)
0.65 (0.58–0.73)
<0.001
0.61 (0.58–0.63)
<0.001
<0.001
Three levels hierarchical mixed effects models were generated (patient level factors nested within institutional level
factors) with the unique hospital identification number incorporated as random effects. Primary and secondary outcome
was adjusted for institutional level variables like annual institutional volume hospital region (Northeast, South, Midwest
with West as referent), teaching vs. nonteaching hospital, and patient-level variables like age, sex, Deyo modification
of Charlson comorbidity index, myocardial infarction, shock, emergent/urgent vs elective admission, admission over
the weekend, median household income, primary payer (with Medicare/Medicaid considered as referent), in addition
to annual operator and institutional procedure volume. Operator and institutional volume were calculated based on the
unique operator and hospital identification number on year to year basis. CI indicates confidence interval; HMO, health
maintenance organization; IABP, intra-aortic balloon pump; and OR, odds ratio.
*Charlson/Deyo comorbidity index was calculated as per Deyo classification.
volume and outcomes became statistically nonsignificant once
operator volume was added to the model (Table 4).
Spline relationship between institutional volume and primary
and secondary outcomes is demonstrated in Figure 5. Predicted
probability of mortality dropped with increasing institutional
volume. Hospitals performing ≤750 PCIs per year had significantly higher mortality rate than hospitals performing >750 PCIs
per year (Figure 5C). A similar relationship was seen for annual
institutional volume and secondary outcome (Figure 5D).
Other Predictors of Outcomes
Other independent predictors of primary and secondary outcomes were increasing age, female sex, increasing Charlson
score, presence of myocardial infarction or shock at the time of
presentation, emergent/urgent admission, use of assist devices,
Badheka et al Percutaneous Coronary Intervention 1401
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Figure 5. Association between Institutional and operator volume for primary and secondary outcomes. A, Spline relationship between
operator volume and primary outcome. B, Spline relationship between operator volume and secondary outcome. C, Spline relationship
between Institutional volume and primary outcome. D, Spline relationship between Institutional volume and secondary outcome.
and insurance status (self-pay or no insurance versus Medicare/
Medicaid). Although increasing quartiles of institutional volume were associated with decreasing in-hospital mortality and
secondary outcomes, this association lost statistically significant after adjusting for other confounding factors.
the odds of primary and secondary outcomes across all subgroups
except in shock when compared with the procedures performed
by operators in the 1st quartile of operator volume. Only highest quartile of operator volume was associated with significant
reduction in the odds of primary outcome (Tables 7 and 8)
Annual Operator Volume and Outcomes in Selected
Subgroups
Length of Stay and Cost of Hospitalization
On multivariable analysis, significant predictors of increased
length of hospital stay were presence of shock/myocardial infarction, increasing CCI, emergent/urgent admission, and weekend
Procedures performed by operators in the 2 , 3 , and 4 quartiles
of operator volume were associated with significant reduction in
nd
rd
th
Table 5. Adjusted Rates for the Primary and Secondary Outcomes, According to Various Institutional and Operator Quartiles
Cutoffs
Operator Quartiles
Institutional
Quartiles
Overall
Primary Outcome
Secondary Outcome
Overall
1 Quartile
(≤15)
2 Quartile
(16–44)
3 Quartile
(45–100)
4 Quartile
(>100)
st
nd
rd
th
Overall
1 Quartile
(≤15)
2nd Quartile
(16–44)
3rd Quartile
(45–100)
4th Quartile
(>100)
5.52
st
-
1.62
1.06
0.78
0.48
-
10.94
7.77
6.38
1st quartile (≤542)
1.46
1.86
1.36
1.06
0.71
8.86
11.08
8.13
6.49
5.66
2nd quartile
(543–914)
1.06
1.63
1.08
0.83
0.54
7.74
10.92
7.75
6.25
5.25
3rd quartile
(917–1641)
0.84
1.42
0.90
0.75
0.50
7.63
11.08
7.85
6.99
5.80
4th quartile (>1641)
0.59
1.17
0.63
0.56
0.40
6.46
10.41
6.93
5.73
5.42
1402 Circulation October 14, 2014
Table 6. Adjusted Rates for the Primary and Secondary
Outcomes, According to Various Institutional and Operator
Volume Cutoffs
Operator Volume
Primary Outcome
Institutional
Overall ≤50 50–75 >75
Volume
Secondary Outcome
Overall
≤50
50–75
>75
Overall
-
1.31
0.78
0.54
-
9.15
6.41
5.73
≤200
1.83
1.88
1.27
0.88
10.01
10.27
6.77
6.07
200–400
1.40
1.55
1.21
0.80
8.72
9.50
6.90
5.95
>400
0.88
1.19
0.73
0.53
7.39
8.96
6.36
5.72
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admission whereas length of stay was negatively associated with
increased operator volume and institutional volume (Table 9).
Similarly, significant predictors of increased cost of care were
presence of shock/myocardial infarction, increasing CCI,
emergent/urgent admission, and weekend admission whereas
increased operator volume and institutional volume were negatively associated with an increased cost of care (Table 9).
Discussion
This study describes one of the largest (a total of 457 498 PCI
procedures, representing a total of 2 243 209 procedures across
the United States) real-world experiences with PCI over a recent
era (2005–2009).We demonstrate a statistically significant
decline in the primary and secondary outcomes with increasing annual operator volume of PCIs. This relationship was also
seen in subgroups of patients with CCI score ≥2, emergent/
urgent admission, myocardial infarction or shock, assist device
use, and multivessel disease. The benefit of increasing operator and hospital volume was also noted in decreasing length of
stay and cost of hospitalization. Our results are consistent with
those based on the NCDR CathPCI Registry (2009), which
demonstrated increase in-hospital mortality among patients
treated by operators performing <75 PCIs/yr. The NCDR
CathPCI data are American College of Cardiology’s most comprehensive outcomes-based quality improvement program and
NCDR CathPCI Registry is limited to voluntarily participating
hospitals. The NIS is the largest publicly available all-payer
inpatient care database in the United States, and includes data
on ≈20% sample of US community including for nonfederal,
short-term, general, and specialty hospitals. Another unique
characteristic of the current study is inclusion of end points
such as length of stay and cost of hospitalization. The relationship of these outcomes and operator or institutional volume has
not been shown earlier.6–21,35
Our study demonstrates a statistically significant inverse
association between operator volume and outcome (in-hospital
mortality and peri-procedural complications) in the current
practice. Our results are in agreement with results from previous studies done both in the percutaneous transluminal coronary angioplasty and the stent era.6–21,35,36 Previous studies have
been limited by the number of centers,12,20 state-based registry
data,8,14,15,18 inclusion of only limited cohorts,16 lower sample
size,8,9,11–18,20 foreign studies,11,19,21 and most importantly they
lack data from recent era.6,7,9,16 Previous studies, which have
shown a decrease in mortality with increasing operator volume, have failed to reach statistical significance because of low
Figure 6. Crude mortality rate and complication rate according to
quartiles of Institutional volume.
sample size, large confidence interval, or low procedure related
mortality.15,22–24 Two prior studies have previously evaluated
the association of institutional volume and outcome from the
NIS database.10,13 These studies, however, did not evaluate the
occurrence of complications and included data from 1998 to
2000 and 2000 to 2003, respectively (pre-COURAGE [Clinical
Outcomes Utilizing Revascularization and Aggressive Drug
Evaluation trial] period).10,13 In general, only a limited number
of studies have previously evaluated the relationship between
PCI volume and complications, with most studies limited to
only post-PCI coronary artery bypass graft.6,16 An additional
strength of our study was the comprehensive definition of periprocedural complications accounting for all major post PCI–
related complications similar to previous published analyses.31
Over the last decade interventional cardiologists have witnessed a decline in the procedural volume3,4 (Figures 2 and 3).
Some studies have questioned the association between operator/institutional volume and adverse outcome in the current era
of technological advancements.17 The 2011 ACCF/AHA/SCAI
PCI guideline recommended that PCI should be performed by
operators with an acceptable annual volume (>75 procedures) at
high-volume centers (>400 procedures) with onsite cardiac surgery.2 These volume recommendations were carried over from
the 2007ACCF/AHA/SCAI competency statement but downgraded to a Level of Evidence C, recognizing that they represent expert opinion and lack strong and consistent evidence.1
The current recommendations for interventional cardiologists
are to perform a minimum of 50 coronary interventional procedures per year (averaged over a 2-year period) and a hospital
minimum of 200 PCI/yr to maintain competency.5 The 2013
competency statement on PCI recognizes the inherent limitation of the currently available data and states that the current
recommendations are primarily established by expert opinion.5
We noted that patients undergoing PCI would experience a
0.53% absolute risk reduction in mortality, after adjustment
for other clinical variables, in the hands of an operator with
annual PCI volume of 50 to 75 procedures/yr as compared
with an operator with annual volume of <50 procedures/yr. A
further 0.24% absolute risk reduction was noted with operators performing >75 procedures/yr as compared with operators who performed 50 to 75 procedures/yr. We also found
that patients undergoing PCI experience a 2.74% absolute risk
Badheka et al Percutaneous Coronary Intervention 1403
Table 7. Annual Operator Volume and Primary Outcome in Selected Subgroups
1st Quartile (≤15)
2nd Quartile (16–44)
OR (95% CI, P Value)
3rd Quartile (45–100)
OR (95% CI, P Value)
4th Quartile (>100)
OR (95% CI, P Value)
Charlson score ≥2*
Referent
0.86 (0.78–0.94, 0.001)
0.80 (0.72–0.89, <0.001)
0.68 (0.60–0.78, <0.001)
Emergent/urgent admission
Referent
0.83 (0.76–0.91, <0.001)
0.85 (0.77–0.94, 0.002)
0.70 (0.62–0.78, <0.001)
Myocardial infarction or shock
Referent
0.87 (0.80–0.95, 0.002)
0.89 (0.81–0.98, 0.020)
0.79 (0.67–0.85, <0.001)
Myocardial infarction
Referent
0.88 (0.79–0.97, 0.014)
0.96 (0.76–0.96, 0.010)
0.69 (0.59–0.80, <0.001)
Shock
Referent
0.96 (0.84–1.08, 0.473)
1.06 (0.92–1.22, 0.451)
0.79 (0.66–0.93, 0.006)
Assist devise use
Referent
0.90 (0.79–1.04, 0.166)
0.92 (0.78–1.07, 0.278)
0.66 (0.55–0.80, <0.001)
Multivessel
Referent
0.94 (0.76–1.16, 0.540)
0.94 (0.75–1.20, 0.635)
0.80 (0.62–1.05, 0.105)
CI indicates confidence interval; and OR, odds ratio.
*Charlson/Deyo comorbidity index was calculated as per Deyo classification.
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reduction in secondary outcome with operator PCI volume
of 50 to 75 procedures/yr as compared with an operator with
annual volume of <50 procedures/yr. A further 0.68% absolute risk reduction was noted in the hands of operators performing >75 procedures/yr as compared with operators who
performed 50 to 75 procedures/yr (Table 6, Figure I in the
online-only Data Supplement).15
Another important finding of this study was an increase
in-hospital mortality in institutions with <200 PCIs/yr when
compared with that of institutions with 200 to 400 and >400
PCIs/yr. Few of the previous studies have reported a combined effect of institutional and operator volume on PCI outcomes.19,37 These studies have shown contradictory results,
with 1 study showing operator volume to be more predictive
of outcomes37 whereas the other did not.19 We found both the
operator and institutional volume to be individually predictive
of outcome when not controlled for the other variable (Table 4
and Table III in the online-only Data Supplement).
A large body of evidence supports the existence of a relationship between hospital volume of PCI and outcome, although
only a few such studies relate total hospital PCI volume to outcome of acute myocardial infarction.21,38 Spaulding et al38 examined the relationship between hospital PCI volume and outcomes
after emergency PCI procedures from the French Registry; a
clear inverse relationship existed between hospital volume and
mortality for emergency PCIs, which persisted after multivariable adjustment. In our study increasing institutional volume
was also associated with improved outcomes. In another study
by Zahn et al,21 a small but significant inverse operator volume–
outcome relationship existed for in-hospital mortality among
patients presenting with acute myocardial infarction. Similarly,
Srinivas et al examined the impact of annual hospital and
physician volume on risk adjusted mortality in 7321 patients
undergoing PCI for acute myocardial infarction from the New
York State PCI Registry (2000–2002). High-volume operators performing >10 PPCIs (Primary PCIs)/yr demonstrated a
34% reduction in risk-adjusted mortality, compared with their
low-volume counterparts.37 The 2011 ACCF/AHA/SCAI PCI
guideline recommends that PCI for ST–segment-elevation
myocardial infarction be performed by experienced operators
who perform >11 PPCI procedures per year, and ideally, these
procedures should be performed at facilities that perform >36
PPCI procedures annually.2 Consistent with previous data, on
subgroup analysis we also found an association between higher
operator volume and outcome (both primary and secondary) in
patient with acute myocardial infarction/ shock. We have shown
that the volume–outcome relationship still exists in a recent era,
and is substantial among high-risk patients undergoing emergency and complex PCI procedures.
Although PCI outcomes have improved and volume has
declined over the years,17 the relationship between PCI volume and outcome still seems intact. One reason for this finding could be higher volume physicians being well versed with
clinical practice guidelines, implementing them more often. As
evident in the study by Srinivas et al,37 the higher volume centers were also more likely to follow evidence-based guidelines.
Another reason could be familiarity with treating PCI complications and emergencies among higher volume physicians.
High-volume hospitals are also likely to have higher-volume
operators and, consequently, experience better outcomes.39
Table 8. Annual Operator Volume and Secondary Outcome in Selected Subgroups
1st Quartile (≤15)
2nd Quartile (16–44)
OR (95% CI, P Value)
3rd Quartile (45–100)
OR (95% CI, P Value)
4th Quartile (>100)
OR (95% CI, P Value)
Charlson score ≥2*
Referent
0.74 (0.71–0.78, <0.001)
0.63 (0.60–0.66, <0.001)
0.59 (0.56–0.62, <0.001)
Emergent/urgent admission
Referent
0.79 (0.77–0.82, <0.001)
0.70 (0.67–0.73, <0.001)
0.63 (0.61–0.66, <0.001)
Myocardial infarction or shock
Referent
0.82 (0.78–0.85, <0.001)
0.76 (0.73–0.80, <0.001)
0.71 (0.67–0.76, <0.001)
Myocardial infarction
Referent
0.79 (0.75–0.84, <0.001)
0.72 (0.67–0.76, <0.001)
0.64 (0.59–0.69, <0.001)
Shock
Referent
0.86 (0.76–0.96, 0.008)
0.81 (0.71–0.92, 0.002)
0.68 (0.58–0.80, <0.001)
Assist devise use
Referent
0.80 (0.71–0.90, <0.001)
0.75 (0.65–0.85, <0.001)
0.57 (0.49–0.66, <0.001)
Multivessel
Referent
0.78 (0.72–0.84, <0.001)
0.72 (0.66–0.78, <0.001)
0.64 (0.59–0.70, <0.001)
CI indicates confidence interval; and OR, odds ratio.
*Charlson/Deyo comorbidity index was calculated as per Deyo classification.
1404 Circulation October 14, 2014
Table 9. Multivariate Predictors of Length of Stay and Cost of Hospitalization
Logarithmic Scale
of Length of Stay
Logarithmic Scale of
Cost of Hospitalization
OR (95% CI)
P Value
OR (95% CI)
P Value
Age (10-yr increment)
1.00 (1.00–1.01)
<0.001
1.02 (1.02–1.02)
<0.001
Female
0.98 (0.98–0.98)
<0.001
0.99 (0.99–0.99)
<0.001
Shock
1.07 (1.06–1.08)
<0.001
1.35 (1.34–1.37)
<0.001
Myocardial infarction
1.07 (1.07–1.08)
<0.001
1.12 (1.12–1.13)
<0.001
Variables
Charlson score
0
Referent
1
1.02 (1.02–1.02)
<0.001
1.03 (1.03–1.03)
Referent
<0.001
≥2
1.06 (1.05–1.06)
<0.001
1.13 (1.13–1.14)
<0.001
<0.001
1.00 (1.00–1.00)
0.385
Primary payer
Medicare/Medicaid
Referent
Referent
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Private including HMO
1.01 (1.01–1.01)
Self pay/no charge/other
0.99 (0.99–1.00)
0.02
0.99 (0.98–0.99)
<0.001
Teaching vs nonteaching hospital
1.03 (1.02–1.04)
<0.001
1.02 (1.01–1.03)
<0.001
Weekend vs weekday admission
1.04 (1.04–1.05)
<0.001
1.08 (1.08–1.08)
<0.001
Emergent/urgent vs elective admission
1.06 (1.06–1.07)
<0.001
1.13 (1.12–1.13)
<0.001
Use of assist devise
1.28 (1.27–1.29)
<0.001
1.42 (1.41–1.44)
<0.001
Institutional volume (quartile)
1st quartile (≤542)
Referent
Referent
2nd quartile
(543–914)
0.96 (0.95–0.97)
<0.001
0.97 (0.96–0.98)
<0.001
3rd quartile
(917–1641)
0.92 (0.91–0.93)
<0.001
0.93 (0.92–0.94)
<0.001
4th quartile (>1641)
0.95 (0.94–0.96)
<0.001
0.97 (0.96–0.99)
<0.001
Operator volume (quartile)
1st quartile
(1–15)
Referent
Referent
2nd quartile
(16–44)
0.97 (0.96–0.97)
<0.001
0.91 (0.91–0.91)
<0.001
3rd quartile
(45–100)
0.95 (0.94–0.95)
<0.001
0.88 (0.87–0.88)
<0.001
4th quartile (>100)
0.95 (0.94–0.95)
<0.001
0.87 (0.87–0.87)
<0.001
Three levels hierarchical mixed effects models were generated (patient level factors nested within hospital level factors) with the
unique hospital identification number incorporated as random effects. Length of stay was adjusted for hospital-level variables like
annual institutional volume, hospital region (Northeast, South, Midwest with West as referent), teaching vs. nonteaching hospital, and
patient level variables like age, sex, Deyo modification of Charlson comorbidity index, myocardial infarction, shock, emergent/urgent
vs elective admission, admission over the weekend, median household income, primary payer (with Medicare/Medicaid considered as
referent), in addition to annual operator and institutional procedure volume. Operator and institutional volume were calculated based
on the unique operator and Institutional identification number on year to year basis. CI indicates confidence interval; HMO, health
maintenance organization; and OR, odds ratio.
Limitations
Although the NIS sampling design is statistically sound and
has been previously used in research to estimate national health
care trends, the clinical data may have some inaccuracies. It is
difficult to validate individual ICD-9 codes because NIS is a
deidentified database making it susceptible to errors related to
coding. The operator volume data can also be misrepresented
because operators could also be performing PCI in hospitals
that were not part of the NIS database. In addition, not all
hospitals allow the release of operator-specific data. Operator
identification numbers were released in only 23 states, which
led to exclusion of large number of procedures. The baseline
characteristics of excluded subjects were, however, similar to
those of included subjects (Table V in the online-only Data
Supplement). Although principal diagnosis is accurately coded
in administrative data, secondary or comorbid diagnoses are
often under-reported, which may explain lower prevalence of
comobidities such as anemia, obesity, and congestive heart
failure in our study. Finally, we lack hemodynamic, echocardiographic, and postdischarge long-term follow-up data, which
could plausibly provide further information regarding safety
and efficacy of PCI. Being an observational study, a causal
relation between the volume of patients and the outcome of
Badheka et al Percutaneous Coronary Intervention 1405
treatment cannot be made. Despite these limitations, our study
represents real-world experience with a large sample size. It is
free from selection bias, which is associated with clinical trials.
In conclusion, we report data from multiple hospitals across
the nation on the association of increasing operator volume
with a decreasing PCI-related in-hospital mortality, procedural complications, length of stay, and cost of hospitalization.
Disclosures
None.
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Clinical Perspective
There has been a recent decline in total number of percutaneous coronary interventions (PCIs) performed. Many interventional cardiologists and hospitals have therefore experienced a fall in procedural volumes. The current clinical competency
guidelines are primarily based on expert opinion because there is paucity of data regarding effects of operator or institutional
volume on outcomes. We assessed the current recommendations in this cross-sectional study consisting of 457 498 PCI
procedures (representing a total of 2 243 209 PCIs performed in the United States during 2005–2009) from multiple hospitals across the nation. We found that procedures performed by high-volume operators and at high-volume institutions have
significant impact on mortality, complications, length of hospital stay, and hence the total cost of in-hospital care. We also
report other patient- and hospital-related factors affecting the outcomes during PCI-related hospitalizations.
Go to http://cme.ahajournals.org to take the CME quiz for this article.
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Impact of Annual Operator and Institutional Volume on Percutaneous Coronary
Intervention Outcomes: A 5-Year United States Experience (2005−2009)
Apurva O. Badheka, Nileshkumar J. Patel, Peeyush Grover, Vikas Singh, Nilay Patel,
Shilpkumar Arora, Ankit Chothani, Kathan Mehta, Abhishek Deshmukh, Ghanshyambhai T.
Savani, Achint Patel, Sidakpal S. Panaich, Neeraj Shah, Ankit Rathod, Michael Brown, Tamam
Mohamad, Frank V. Tamburrino, Saibal Kar, Raj Makkar, William W. O'Neill, Eduardo De
Marchena, Theodore Schreiber, Cindy L. Grines, Charanjit S. Rihal and Mauricio G. Cohen
Circulation. 2014;130:1392-1406; originally published online September 4, 2014;
doi: 10.1161/CIRCULATIONAHA.114.009281
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 2014 American Heart Association, Inc. All rights reserved.
Print ISSN: 0009-7322. Online ISSN: 1524-4539
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http://circ.ahajournals.org/content/suppl/2014/09/04/CIRCULATIONAHA.114.009281.DC1
http://circ.ahajournals.org/content/suppl/2016/12/29/CIRCULATIONAHA.114.009281.DC2
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SUPPLEMENTARY MATERIAL
Supplementary table 1: Procedural complications of PCI by ICD 9 code.
Any procedural complications
ICD CODE
Vascular complications
1) Post-op hemorrhage requiring transfusion
2) Vascular complications including
99.0
-Injury to blood vessels-900-904
-Accidental puncture-998.2, e8700-8709 (PSI)
-AV fistula-447
-Injury to retro-peritoneum 8680.4
-Vascular complications requiring surgery-39.31,
39.41, 39.49, 39.52, 39.53, 39.56, 39.57, 39.58,
39.59, 39.79
-Other vascular complications-999.2, 997.7
Cardiac complications
1) Iatrogenic cardiac complications
997.1*
2) Pericardial complications
423.0-Hemopericardium
423.3-Cardiac tamponade
37.0-Pericardiocentesis
Requiring CABG
36.1x, 36.2, 36.31, 36.32, 36.9x
Post-op respiratory failure
PSI†
Neurological Complications
Postoperative-Stroke/TIA
997.0, 997.00, 997.01, 997.02, 435.9,
438.0, 4381.0,
4381.1, 4381.2, 4381.9,
4382.0, 4382.1, 4382.2,
4383.0, 4383.1, 4383.2, 4384.0, 4384.1, 4384.2,
4385.0, 4385.1, 4385.2, 4385.3
4388.1, 4388.2, 4388.9, 438.9
Renal and metabolic complications
1) Acute renal failure requiring dialysis
PSI†
2) Acute severe metabolic derangement
PSI†
Postoperative DVT or Pulmonary embolism.
PSI†
Postoperative infectious complications
PSI†
Pressure ulcer rate
PSI†
Anesthetic complications
PSI†
•
Av block 3rd degree, complication of av nodal ablation
•
Av block, complete, post op complication of av nodal ablation
•
Bypass complications
•
Cardiac arrest as a complication of care
•
Cardiac arrest during and/or resulting from a procedure
•
Cardiac complication
•
Cardiac complication of procedure
•
Cardiac insufficiency as a complication of care
•
Cardiac insufficiency during and/or resulting from a procedure
•
Cardiorespiratory failure as a complication of care
•
Cardiorespiratory failure during and/or resulting from a procedure
•
CHF after surgery, early postop complication
•
CHF following cardiac surgery, postop
•
CHF following non-cardiac surgery, postop
•
Complete atrioventricular block due to atrioventricular nodal ablation
•
Congestive heart failure after surgery
•
Congestive heart failure as early postoperative complication
•
Congestive heart failure as postoperative complication of cardiac surgery
•
Congestive heart failure as postoperative complication of non cardiac surgery
•
Heart failure as a complication of care
•
Junctional ectopic tachycardia, postoperative
•
Post cardiac operation functional disturbance
•
Postoperative cardiac complication
•
Postoperative complete heart block
•
Postoperative his bundle tachycardia
•
Postoperative myocardial infarction
•
Postoperative sinoatrial disease
•
Postoperative subendocardial myocardial infarction
•
Postoperative transmural myocardial infarction of anterior wall
•
Postoperative transmural myocardial infarction of inferior wall
•
Recurrent coronary arteriosclerosis after percutaneous transluminal coronary angioplasty
997.1 Excludes
•
the listed conditions as long-term effects of cardiac surgery or due to the presence of cardiac prosthetic device ( 429.4)
Applies To
•
•
Cardiac:
o
arrest during or resulting from a procedure
o
insufficiency during or resulting from a procedure
Cardiorespiratory failure during or resulting from a procedure
Heart failure during or resulting from a procedure
†: Post-procedural complications were identified by Patient Safety Indicators (PSIs) which have been established by the Agency for Healthcare
Research and Quality to monitor preventable adverse events during Institutionalization. These indicators are based on ICD-9-CM codes and
Medicare severity Diagnosis-Related Groups and each PSI has specific inclusion and exclusion criteria PSI individual measure technical
specifications, Version 4.4, March 2012 was used to identify and define preventable complications.
Supplementary table 2: Deyo’s modification of Charlson’s co-morbidity index (CCI).
Reported ICD-9 CM Codes
Condition
Charlson
Score
410 – 410.9
Myocardial infarction
1
428 – 428.9
Congestive heart failure
1
433.9, 441 – 441.9, 785.4, V43.4
Peripheral vascular disease
1
430 – 438
Cerebrovascular disease
1
290 – 290.9
Dementia
1
490 – 496, 500 – 505, 506.4
Chronic pulmonary disease
1
710.0, 710.1, 710.4, 714.0 – 714.2,
Rheumatologic disease
1
531 – 534.9
Peptic ulcer disease
1
571.2, 571.5, 571.6, 571.4 – 571.49
Mild liver disease
1
250 – 250.3, 250.7
Diabetes
1
250.4 – 250.6
Diabetes with chronic complications
2
344.1, 342 – 342.9
Hemiplegia or paraplegia
2
582 – 582.9, 583 – 583.7, 585, 586,
Renal disease
2
588 – 588.9
140-172.9, 174-195.8, 200-208.9
Any malignancy including leukemia and
2
714.81, 725
lymphoma
572.2 – 572.8
Moderate or severe liver disease
3
196-199.1
Metastatic solid tumor
6
042 – 044.9
AIDS
6
Supplementary table 3: Multivariate predictors of primary and secondary outcomes for institutional volume only.
Patients
Study Population with and without operator ID (n-839,883)
Primary Outcome
Secondary Outcome
Study Population with operator ID (n-457498)
Primary Outcome
Secondary Outcome
Study Population without operator ID (n-382385)
Primary Outcome
Secondary Outcome
OR(95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
Age (10 year increment)
1.59(1.55-1.63)
<0.001
1.12(1.10-1.13)
<0.001
1.60 (1.55-1.66)
<0.001
1.12 (1.10-1.13)
<0.001
1.58(1.52-1.64)
<0.001
1.11(1.09-1.13)
<0.001
Female
1.17(1.11-1.23)
<0.001
1.26(1.23-1.29)
<0.001
1.21 (1.13-1.29)
<0.001
1.28 (1.25-1.31)
<0.001
1.11(1.04-1.20)
0.004
1.24(1.20-1.27)
<0.001
Shock
14.41(13.08-15.88)
<0.001
7.68(7.27-8.11)
<0.001
14.54 (13.33-
<0.001
7.66 (7.25-8.10)
<0.001
14.13(12.22-16.34)
<0.001
7.49(6.92-8.11)
<0.001
Myocardial infarction
3.97(3.63-4.34)
<0.001
1.73(1.68-1.79)
<0.001
15 86)
3.99 (3.60-4.42)
<0.001
1.75 (1.70-1.80)
<0.001
3.89(3.43-4.42)
<0.001
1.71(1.63-1.79)
<0.001
Charlson score€
0
Referent
Referent
Referent
Referent
Referent
Referent
1
2.21(1.87-2.61)
<0.001
1.48(1.42-1.55)
<0.001
2.36(1.88-2.95)
<0.001
1.47 (1.41-1.54)
<0.001
2.00(1.55-2.59)
<0.001
1.46(1.36-1.57)
<0.001
>=2
3.38(2.85-4.00)
<0.001
2.93(2.76-3.11)
<0.001
3.72(2.97-4.64)
<0.001
2.85 (2.73-2.98)
<0.001
2.99(2.30-3.88)
<0.001
2.92(2.67-3.18)
<0.001
Median house hold income
1st quartile
Referent
2nd quartile
0.95(0.88-1.02)
0.1585
0.98(0.94-1.01)
0.1915
0.99 (0.91-1.08)
0.841
1.00 (0.97-1.04)
0.884
0.95(0.86-1.05)
0.3303
0.94(0.90-0.99)
0.0118
3rd quartile
0.93(0.86-1.00)
0.0607
1.01(0.97-1.05)
0.7072
1.01(0.92-1.11)
0.823
1.02 (0.99-1.06)
0.231
0.91(0.82-1.00)
0.0591
0.96(0.91-1.01)
0.1403
4th quartile
0.85(0.77-0.93)
0.0004
0.96(0.90-1.02
0.2103
0.94(0.84-1.04)
0.222
0.99 (0.95-1.03)
0.714
0.88(0.78-0.98)
0.0188
0.93(0.87-0.99)
0.0183
Referent
Referent
Referent
Referent
Referent
Primary Payer
Medicare / Medicaid
Referent
Referent
Referent
Referent
Referent
Referent
Private including HMO
0.79(0.73-0.85)
<0.001
0.76(0.74-0.78)
<0.001
0.77(0.70-0.85)
<0.001
0.78 (0.76-0.81)
<0.001
0.80(0.71-0.89)
<0.001
0.73(0.70-0.76)
<0.001
Self pay/no charge/other
1.20(1.09-1.32)
0.0003
0.82(0.78-0.86)
<0.001
1.23(1.08-1.40)
0.002
0.82 (0.78-0.87)
<0.001
1.13(0.98-1.31)
0.1033
0.78(0.73-0.84)
<0.001
Teaching vs non-teaching
1.03(0.96-1.11)
0.4459
1.04(0.98-1.10)
<0.001
1.02(0.92-1.12)
0.751
1.05 (0.99-1.11)
0.123
1.16(1.04-1.28)
0.0055
1.06(0.98-1.14)
0.1851
h vs itWeekdays
l
Weekend
1.07(1.00-1.13)
0.0416
1.02(1.00-1.05)
<0.001
1.07(0.99-1.15)
0.098
1.02 (0.99-1.06)
0.169
1.05(0.96-1.14)
0.2834
1.01(0.98-1.05)
0.5332
d i i vs. elective
Emergent/urgent
1.39(1.27-1.52)
<0.001
1.03(0.99-1.08)
0.127
1.49(1.34-1.66)
<0.001
1.08 (1.05-1.12)
<0.001
1.37(1.20-1.57)
<0.001
1.00(0.95-1.06)
0.9546
d i i
Use of assist devise or IABP
3.22(2.90-3.59)
<0.001
2.61(2.44-2.78)
<0.001
3.37(3.07-3.69)
<0.001
2.64 (2.50-2.80)
<0.001
3.24(2.76-3.80)
<0.001
2.71(2.49-2.95)
<0.001
Institutional volume
(Q
til )
1st Quartile (<=436)
Referent
2nd Quartile (442-770)
0.94(0.87-1.03)
0.1876
0.97(0.92-1.03)
0.2861
0.91(0.81-1.01)
0.077
0.91 (0.86-0.97)
0.002
0.88(0.78-0.99)
0.032
0.95(0.89-1.02)
0.1798
3rd Quartile (771-1320)
0.82(0.75-0.90)
<0.001
0.96(0.89-1.04)
0.3601
0.82(0.72-0.93)
0.002
0.92 (0.86-0.99)
0.024
0.80(0.71-0.91)
0.0005
0.96(0.88-1.06)
0.4537
4th Quartile (>=1325)
0.74(0.66-0.83)
<0.001
0.90(0.83-0.99)
0.0211
0.78(0.66-0.92)
0.002
0.86 (0.79-0.94)
0.001
0.71(0.59-0.85)
0.0003
0.86(0.74-1.01)
0.0606
Referent
Referent
Referent
Referent
Referent
OR indicates Odds Ratio, CI indicates Confidence interval, HMO indicates Health Maintenance Organization. IABP indicates Intra-Aortic
Balloon Pump.
€: Charlson's/deyo comorbidity index was calculated as per Deyo classification.
Three levels hierarchical mixed effects models were generated (patient level factors nested within institutional level factors) with the unique
hospital identification number incorporated as random effects. Primary and secondary outcome was adjusted for institutional level variables like
annual institutional volume hospital region (Northeast, South, Midwest with West as referent), teaching vs. non-teaching hospital, and patient level
variables like age, sex, Deyo modification of CCI, myocardial infarction, shock, emergent/urgent vs elective admission, admission over the
weekend, median house hold income, primary payer (with Medicare/Medicaid considered as referent), in addition to annual institutional procedure
volume.
Supplementary Table 4: Model performances
Primary Outcome
Secondary Outcome
C statistics
Model
AIC
Wald Chi
BIC
AIC
(95% CI)
square
C statistics
Chi
(95% CI)
square
BIC
Overall
35374.94
35638.93
0.91(0.90-0.91)
15056.57
207715.00
207979.00
0.75(0.75-0.76)
25660.53
Emergent/urgent Admission
30724.52
30968.28
0.69(0.68-0.69)
12162.91
153028.00
153271.80
0.75(0.75-0.76)
19113.98
Charlson score >=2*
23912.16
24131.08
0.90(0.89-0.90)
7992.91
109532.60
109751.50
0.74(0.74-0.75)
10261.51
Multivessel
5543.74
5762.81
0.90(0.90-0.91)
2480.14
35696.43
35915.50
0.75(0.75-0.76)
4093.77
Assist devise use
8218.72
8383.88
0.77(0.77-0.78)
817.25
11874.14
12039.30
0.74(0.74-0.75)
1088.97
29267.02
29484.50
0.83(0.83-0.84)
6854.27
95346.45
95563.94
0.73(0.73-0.74)
9792.70
Myocardial infarction
18363.27
18566.17
0.84(0.83-0.84)
3920.35
52868.97
53071.87
0.73(0.73-0.74)
5677.07
Shock
9420.71
9582.4
0.67(0.66-0.68)
386.71
10942.71
11104.5
0.62(0.61-0.62)
307.44
Myocardial infarction and or
shock
Supplementary table 5:- Baseline characteristics of the excluded patients, according to quartiles of annual institutional volume.
1st quartile
Demographic variable
2nd quartile
3rd quartile
4th quartile
Overall
P Value
(<=542)
(543 – 914)
(917 – 1641)
(>1641)
Pci unweighted no.*
382385
124241(32.5%) 104587(27.4%) 101146(26.5%) 52411(13.7%)
Pci weighted no.†
1896419
611367(32.2%) 515097(27.2%) 511410(27.0%) 258545(13.7%)
64.37±0.02
64.15+0.04
Patient level variables
Age (mean ± SE)
64.61+0.04
64.29+0.04
64.54+0.05
<0.001
<0.001
Gender (%)
Male
66.43
65.93
66.25
66.58
67.66
Female
33.57
34.07
33.75
33.42
32.34
<0.001
Race (%)
White
51.83
55.14
54.97
47.4
46.53
Non-white
14.43
20.41
13.4
10.2
10.7
Comorbidities* (%)
Charlson Comorbidity index
<0.001
0
21.19
18.51
21.04
23.14
23.97
1
39.32
39.79
39.56
38.91
38.53
>=2
39.5
41.71
39.4
37.9
37.5
<0.001
History of Obesity
11.56
11.68
11.54
10.96
12.49
<0.001
History of hypertension*
68.52
67.67
67.93
68.65
71.47
<0.001
History of diabetes *
32.36
32.95
32.39
31.53
32.58
<0.001
0.88
1.15
0.94
0.74
0.44
<0.001
pulmonary disease*
14.85
14.89
14.96
14.63
14.98
<0.001
Peripheral vascular disease *
9.96
9.73
10.28
9.37
11.04
<0.001
History of congestive heart
failure*
History of chronic
Fluid-electrolyte
abnormalities and or Renal
failure *
15.16
17.09
15.28
13.64
13.37
<0.001
paralysis*
3.32
3.61
3.37
3.04
3.1
<0.001
Anemia or coagulopathy*
8.22
9.61
8.32
6.99
7.2
<0.001
oncological malignancy *
1.52
1.58
1.53
1.53
1.37
<0.001
Weight loss*
0.65
0.77
0.7
0.51
0.52
<0.001
collagen vascular Disease *
1.74
1.75
1.79
1.7
1.72
0.0137
History of Valvular disorder
0.26
0.3
0.31
0.19
0.19
<0.001
7.37
7.7
7.22
7.16
7.33
<0.001
Neurological disorder or
Hematological or
Rheumatoid arthritis or other
Depression, psychosis or
substance abuse*
Median household income
category for patient's zip
<0.001
code ¥
1. 0-25th percentile
22.8
23.07
23.63
23.34
19.48
2. 26-50th percentile
26.13
26.83
25.67
26.77
24.14
3. 51-75th percentile
25.94
24.69
25.34
27.51
27
4. 76-100th percentile
22.97
23.16
23.17
20.38
27.23
<0.001
Primary Payer
Medicare / Medicaid
55.31
54.59
56.09
55.45
55.21
Private including HMO
36.66
35.23
35.93
37.8
39.27
Self pay/no charge/other
7.87
9.97
7.86
6.68
5.27
Hospital characteristics
Hospital bed size£
<0.001
Small
7.58
12.37
5.51
1.68
12.07
Medium
19.8
30.42
12.85
13.92
20.15
Large
72.19
55.88
81.64
84.4
67.78
<0.001
Hospital Location
Rural
5.31
8.41
6.39
3.2
0
Urban
94.26
90.26
93.61
96.8
100
<0.001
Hospital Region
Northeast
13.25
8.6
11.73
24.99
4.02
Midwest or North Central
37.11
38.13
38.72
35.31
35.01
South
28
25.13
22.59
29.49
42.64
West
21.65
28.14
26.95
10.21
18.33
<0.001
Hospital Teaching status
Non-teaching
45.11
59.11
49.28
28.74
36.11
Teaching
54.46
39.56
50.72
71.26
63.89
<0.001
Admission types (%)
Emmergent/Urgent
60.15
59.85
58.43
70.9
43.02
Elective admission
22.5
18.71
21.84
19.54
38.63
Unknown/missing
17.35
21.44
19.72
9.56
18.34
<0.001
Admission day (%)
Weedays
84.49
82.1
84.18
85.23
89.29
Weekend
15.51
17.9
15.82
14.77
10.71
Length of stay(Mean±SE)
3.02±0.01
3.32±0.01
3.02±0.01
2.97±0.01
2.45±0.01
<0.001
Total Adjusted cost
17506±10
19778±24
18128±30
17645±29
13994±54
<0.001
<0.001
Disposition
Home
93.98
92.57
94.03
94.72
95.77
Facility/others
4.39
5.42
4.37
3.82
3.13
Death
1.29
1.58
1.28
1.16
0.86
<0.001
Vessel involved
Single vessel single stent
57.88
60.7
59.67
55.2
52.51
stent
19.8
19.16
19.73
20.67
19.87
Stent on vessel bifurcation
2.47
2.1
2.05
2.91
3.41
Multivessel
19.85
18.04
18.55
21.22
24.21
Cardiopulmonary Shock
2.51
3.05
2.44
2.26
1.84
<0.001
AMI
43.72
49.12
43.24
41.83
35.68
<0.001
Fractional flow reserve
0.31
0.41
0.35
0.26
0.12
<0.001
Intravascular ultrasound
4.6
4.76
4.41
3.78
6.23
<0.001
Single vessel more than 1
SE indicates standard error. HMO indicates Health Maintenance Organization. AMA indicates Against Medical Advice. AMI indicates Acute
Myocardial Infarction. IABP indicates Intra Aortic Balloon Pump.
* No. of Unweighted PCI
† No. of Weighted PCI
§ Variables are AHRQ comorbidity measures.
|| Charlson/Deyo comorbidity index was calculated as per Deyo classification.
# This represents a quartile classification of the estimated median household income of residents in the patient's ZIP Code. These values are
derived from ZIP Code-demographic data obtained from Claritas. The quartiles are identified by values of 1 to 4, indicating the poorest to
wealthiest populations. Because these estimates are updated annually, the value ranges vary by year.
http://www.hcupus.ahrq.gov/db/vars/zipinc_qrtl/nisnote.jsp
£: The bed size cutoff points divided into small, medium, and large have been done so that approximately one-third of the hospitals in a given
region, location, and teaching status combination would fall within each bed size category. State and County QuickFacts. Washington, DC: US
Census Bureau; 2012.
Supplementary Figure 1: Adjusted risk for primary and secondary outcomes.
Supplementary Figure Legends
Supplementary Figure 1: Adjusted risk for primary and secondary outcomes.
HCUP Methods Series
2007 HCUP Nationwide Inpatient Sample (NIS) Comparison
Report
Report # 2010-03
Contact Information:
Healthcare Cost and Utilization Project (HCUP)
Agency for Healthcare Research and Quality
540 Gaither Road
Rockville, MD 20850
http://www.hcup-us.ahrq.gov
For Technical Assistance with HCUP Products:
Email: [email protected]
or
Phone: 1-866-290-HCUP
Recommended Citation: Barrett M, Wilson E, Whalen D. 2007 HCUP Nationwide
Inpatient Sample (NIS) Comparison Report. HCUP Methods Series Report # 2010-03. Online
September 9, 2010. U.S. Agency for Healthcare Research and Quality. Available:
http://www.hcup-us.ahrq.gov/reports/methods.jsp.
TABLE OF CONTENTS
Introduction ................................................................................................................................ 1 Summary of NIS-AHA Comparisons ......................................................................................... 3 Summary of NIS-NHDS Comparisons .................................................................................... 10 Summary of NIS-MedPAR Comparisons ................................................................................ 23 References ................................................................................................................................ 41 HCUP (09/3/2010)
NIS Comparison Report, 2007
INDEX OF TABLES
Table 1. Comparison of States in the NIS with National Demographics, 2007 ............................... 2 Table 2. Number of Hospitals in NIS Frame1 and AHA Universe, 2007 .......................................... 4 Table 3. NIS and AHA Comparisons by Facility Services, 2007 ..................................................... 5 Table 4. NIS and AHA Comparisons by Facility Characteristics, 2007 ........................................... 6 Table 5. NIS and AHA Comparisons by Region, 2007 .................................................................... 7 Table 6. NIS and AHA Comparisons by Hospital Control, 2007 ..................................................... 8 Table 7. NIS and AHA Comparisons by Location and Teaching Status, 2007 ............................... 9 Table 8. NIS and NHDS Comparisons by Region, 2007 ............................................................... 11 Table 9. NIS and NHDS Comparisons by Hospital Control, 2007 ................................................. 12 Table 10. NIS and NHDS Comparisons by Patient Characteristics, 2007 .................................... 13 Table 11. NIS and NHDS Comparisons by Principal Payer, 2007 ................................................ 14 Table 12. NIS and NHDS Comparisons by the 25 Most Common Principal Diagnoses, 2007 ..... 16 Table 13. NIS and NHDS Comparisons by the 25 Most Common Principal Procedures, 2007 .... 19 Table 14. NIS and NHDS Comparisons by Infrequent Principal Diagnoses, 2007 ....................... 21 Table 15. NIS and MedPAR Comparisons by Region, 2007......................................................... 24 Table 16. NIS and MedPAR Comparisons by Hospital Control, 2007 .......................................... 25 Table 17. NIS and MedPAR Comparisons by Hospital Location and Teaching Status, 2007 ...... 27 Table 18. NIS and MedPAR Comparisons by Patient Characteristics, 2007 ................................ 28 Table 19. NIS and MedPAR Comparisons by DRG, 2007 ............................................................ 30 Table 20. NIS and MedPAR Comparisons by the 25 Most Common
Principal Diagnoses, 2007 ............................................................................................ 35 Table 21. NIS and MedPAR Comparisons by the 25 Most Common
Principal Procedures, 2007 ........................................................................................... 39 HCUP (09/3/2010)
NIS Comparison Report, 2007
INDEX OF FIGURES
Figure 1. HCUP State Partners Participating in the NIS, 2007 ....................................................... 1 Figure 2. Discharge Estimates for the 25 Most Common Principal Diagnoses, NIS, 2007 ........... 15 Figure 3. Discharge Estimates for the 25 Most Common Principal Procedures, NIS, 2007 ......... 18 Figure 4. Medicare Discharge Estimates for the 25 Most Common DRGs in the NIS, 2007 ........ 29 Figure 5. Medicare Discharge Estimates for the 25 Most Common Principal Diagnoses,
NIS, 2007 ........................................................................................................................ 34 Figure 6. Medicare Discharge Estimates for the 25 Most Common Principal Procedures,
NIS, 2007 ........................................................................................................................ 38 HCUP (09/3/2010)
NIS Comparison Report, 2007
INTRODUCTION
This report provides a summary of analyses that compare estimates from the HCUP Nationwide
Inpatient Sample (NIS) for 2007 to three related data sources: the American Hospital
Association (AHA) Annual Survey Database, the National Hospital Discharge Survey (NHDS)
from the National Center for Health Statistics, and the MedPAR inpatient data from the Centers
for Medicare and Medicaid Services (CMS). For full information on these databases and
complete details on prior years’ findings, refer to earlier versions of this report on HCUP-US
Website under the heading “NIS Comparison Reports” at http://www.hcupus.ahrq.gov/db/nation/nis/nisrelatedreports.jsp.
As shown in Figure 1 and Table 1, the 2007 NIS is selected from a sampling frame comprising
40 HCUP Partner organizations.
Figure 1. HCUP State Partners Participating in the NIS, 2007
WEST
MIDWEST
NORTHEAST
NH
WA
VT
ND
ME
MT
OR
MN
ID
MA
WI
SD
NY
MI
RI
WY
IA
NE
NV
IL
UT
CA
KS
CO
NJ
OH
IN
WV
MO
VA
KY
AZ
OK
AR
SC
MS
AK
DE
MD
DC
NC
TN
NM
CT
PA
AL
GA
LA
TX
FL
SOUTH
HI
The findings in this report are summarized in tables that highlight differences and similarities
between the four databases.
•
Table 1 compares states representing HCUP Partners in the NIS to those in the hospital
universe (the U.S.)
•
Tables 2-7 summarize comparisons with the AHA Annual Survey
•
Tables 8-13 summarize comparisons with the NHDS
•
Tables 14-20 summarize comparisons with MedPAR data
HCUP (09/3/2010)
1
Del #45.1 NIS Comparison Report, 2007
Based on the analyses presented in this report, the NIS appears to provide reliable national
estimates when compared with other national data sources along the dimensions of hospital
characteristics, numbers of discharges, length of stay, and in-hospital mortality.
Each of the data sources discussed has its strengths and weaknesses, and each may be the
preferred choice for different research questions. The NIS offers a large sample that enables
study of low incidence disorders and less common procedures; NIS estimates can be calculated
for literally thousands of sub-populations that may be of interest to researchers. In addition, NIS
hospitals accurately reflect the universe of United States hospitals, particularly the relative mix
of large and small hospitals. Therefore, the NIS may be more appropriate when hospital type
and size are important considerations.
In contrast, the NHDS and MedPAR both offer data drawn from all 50 states, rather than the
more limited sampling frame of the NIS. Where a comprehensive geographic representation is
more important than a large sample size, these resources might be preferable. Alternatively, if
the question under study applies only to Medicare enrollees, the MedPAR data set might be
favored.
Which of the data sources is better? The answer depends on the needs of the researcher. The
intended use of the data is the most critical factor in determining which data source will be most
valuable. In general, the NIS estimates of data elements essential to health care policy –
including in-hospital mortality, inpatient population size, length of stay, and charges – are
accurate and precise. It is possible to calculate statistics for large groups ranging from the
inpatient population of the United States, as well as for small subsets focusing on specific
conditions. The characteristics documented in this report suggest that the NIS produces reliable
estimates and that it is a valuable tool for researchers and policy makers alike.
Table 1. Comparison of States in the NIS with National Demographics, 2007
NIS Sampling Frame
United States
Number of States
40
50 plus District of Columbia
Population
269,763,460
301,621,157
78% of U.S. community
hospitals
100%
81% of community hospital
discharges
100%
90% of U.S. population
100%
Average population density
(persons per square mile)
114.7
84.5
Population density for the
least populated states
(persons per square mile)
Nebraska (23.1)
South Dakota (10.5)
Wyoming (5.4)
Montana (6.6)
Wyoming (5.4)
Alaska (1.2)
Market penetration of
Medicare managed care
providers
18.4%
19.0%
Sampling frame for the NIS
includes
HCUP (09/3/2010)
2
Del #45.1 NIS Comparison Report, 2007
Summary of NIS-AHA Comparisons
ƒ
NIS hospitals resembled typical hospitals in the AHA universe in most characteristics,
although NIS hospitals were more active, had higher and more intensive staffing rates,
and more Medicare- and Medicaid-covered patients.
ƒ
NIS facilities admitted and discharged more patients, and had larger payrolls compared
to hospitals in the AHA universe.
ƒ
NIS hospitals tended to offer slightly more high-technology services than the AHA.
ƒ
Nearly all NIS discharge estimates closely align with the discharge counts from the AHA
Survey. This is not surprising because NIS sampling strata and NIS discharge weights
were based on AHA Annual Survey results.
ƒ
The AHA-derived sampling weights in the NIS yield discharge counts consistent with the
AHA universe by region and for most categories of hospital type. The discharge
comparisons by hospital ownership, exhibited no significant differences.
ƒ
In contrast, the overall NIS estimated average length of stay was slightly longer than the
AHA statistic.
ƒ
Rural hospitals was the one category where the weighted NIS hospital count differed
from the actual AHA hospital count—the NIS includes relatively fewer small rural
hospitals and relatively more large rural hospitals than found in the AHA universe.
ƒ
AHA Annual Survey data reflect admission counts. To be consistent with the other
datasets used for analysis in this report (i.e., based on discharge counts), we adjusted
the AHA Annual Survey admission counts by including admission counts for well
newborns.
HCUP (09/3/2010)
3
Del #45.1 NIS Comparison Report, 2007
Table 2. Number of Hospitals in NIS Frame1 and AHA Universe, 2007
NIS
(Weighted)
5,099
NIS
(Unweighted)
1,054
AHA
U.S.
5,099
Region
Northeast
651
134
651
Midwest
1,487
302
1,487
South
2,032
416
2,032
West
929
192
929
Hospital Control
Public
1,105
228
1,120
Non-Profit
3,003
614
2,918
Proprietary
991
202
1,061
Location / Teaching Status
Rural
2,050
420
2,050
Small
1,030
209
1,323
Mediums
425
88
401
Large
595
123
326
Urban, non-teaching
2,205
450
2,205
Small
1,014
206
1,032
Medium
554
114
593
Large
637
130
580
Urban, teaching
844
174
844
Small
255
53
245
Medium
256
52
241
Large
333
69
358
Note: Significance tests were not performed because AHA numbers are not sample statistics.
1
The 2007 frame contains 40 states.
HCUP (09/3/2010)
4
Del #45.1 NIS Comparison Report, 2007
Table 3. NIS and AHA Comparisons by Facility Services, 2007
NIS
AHA
1
High Tech Index (mean)
2.66
2.58
High Tech Index1 (median)
2.00
2.00
Neonatal ICUs2
18.89%
18.61%
Cardiac Catheterization2
27.35%
26.64%
CT Scanners2
78.45%
74.87%
MRIs2
57.25%
54.83%
2
Open Heart Surgeries
20.81%
21.58%
Transplant Services2
7.25%
7.76%
2
Intensity Modulated Ray Radiation Therapy
19.93%
18.32%
Extracorporeal Shock Wave Lithotripsy2
22.32%
21.89%
2
PET Scanners
13.52%
13.09%
Pediatric Specialty Hospitals
1.06%
1.70%
Burn Units
3.83%
4.38%
Rehabilitation Units
25.30%
24.64%
Alcohol/Chemical Dependancy Services
8.93%
7.13%
Trauma Centers
28.31%
28.97%
Emergency Departments
78.95%
76.28%
Note: Significance tests were not performed because AHA numbers are not sample statistics.
1
Prior to 2004, the index included Angioplasty services.
High technology service - used in the "High Tech Index."
2
HCUP (09/3/2010)
5
Del #45.1 NIS Comparison Report, 2007
Table 4. NIS and AHA Comparisons by Facility Characteristics, 2007
NIS
Mean
7,143.42
7,143.42
8,037.53
5.74
5.33
894.11
54.07
49.16
AHA
Mean
6,902.30
6,902.30
7,687.40
5.89
5.49
785.10
54.51
48.76
NIS
Median
3,290.00
3,290.00
3,612.00
4.31
3.92
310.00
54.31
47.87
AHA
Median
3,154.00
3,154.00
3,494.00
4.38
4.00
248.00
55.66
47.95
Hospital Admissions
Hospital Discharges
Hospital Discharges1
Average Length of Stay
Average Length of Stay1
Births
Percent Medicare Days
Percent Medicare
Discharges
Percent Medicare
45.62
45.42
43.38
43.67
Discharges1
Percent Medicaid Days
15.05
14.54
13.15
12.52
Percent Medicaid
16.18
15.68
15.93
15.08
Discharges
Percent Medicaid
14.51
14.15
14.04
13.54
Discharges1
Hospital Beds
149.18
146.11
82.00
80.00
Occupancy Rate
52.34
52.23
54.19
53.73
Inpatient Surgeries
2,014.30
2,040.69
896.00
892.00
FTE2
926.88
874.98
405.50
396.00
2
FTE per Bed
6.06
5.76
5.43
5.22
2
RN FTE per 1000 Patient
3.93
3.52
3.16
3.09
Days
Intern-Resident FTE2 per
6.77
6.40
0.00
0.00
100 Beds
Intern-Resident FTE2 per
34.81
34.60
11.61
12.08
100 Beds (Teaching
Hospitals)
Total Hospital Expenses
$122,366,800 $112,658,940
$51,407,783
$45,143,250
Hosp. Expenses per Bed
$751,718
$690,442
$651,770
$621,871
Total Hospital Payroll
$49,681,561
$45,406,010
$20,051,934
$18,110,986
Hosp. Payroll per Bed
$301,262
$276,596
$256,525
$245,781
Note: Significance tests were not performed because AHA numbers are not sample statistics.
1
To be consistent with the other datasets used for analysis in this report, AHA Annual Survey
admission counts have been adjusted by including admission counts for well newborns.
2
Full-time equivalents.
HCUP (09/3/2010)
6
Del #45.1 NIS Comparison Report, 2007
Table 5. NIS and AHA Comparisons by Region, 2007
Overall
Region
Northeast
South
Midwest
West
*Significant at p<0.05.
HCUP (09/3/2010)
Number of Discharges in
Thousands
(Standard Error)
NIS
AHA
39,541
40,023
(799)
7,753
7,753
(337)
9,130
9,130
(323)
15,273
15,273
(594)
7,385
7,385
(258)
**Significant at p<0.01.
7
Average Length of Stay in Days
(Standard Error)
NIS
AHA
4.60
4.46**
(0.03)
5.13
(0.08)
4.35
(0.06)
4.62
(0.06)
4.33
(0.08)
5.04
4.26
4.47*
4.06**
Del #45.1 NIS Comparison Report, 2007
Table 6. NIS and AHA Comparisons by Hospital Control, 2007
Total Public
1-99 Beds
100-199 Beds
200-299 Beds
300-499 Beds
500+ Beds
Total Private Non-Profit
1-99 Beds
100-199 Beds
200-299 Beds
300-499 Beds
500+ Beds
Total Proprietary
1-99 Beds
100-199 Beds
200-299 Beds
300-499 Beds
500+ Beds
*Significant at p<0.05.
HCUP (09/3/2010)
Number of Discharges in
Thousands
Average Length of Stay in Days
(Standard Error)
(Standard Error)
NIS
AHA
NIS
AHA
5,667
5,542
4.86
4.7
(693)
(0.16)
1,041
1,060
3.89
3.79
(70)
(0.16)
826
923
4.05
4.23
(130)
(0.12)
645
633
4.16
4.28
(143)
(0.16)
848
1,241
4.99
4.96
(243)
(0.28)
2,305
1,683
5.73
5.53
(383)
(0.27)
28,600
28,587
4.54
4.40**
(965)
(0.03)
2,433
2,617
3.67
3.78
(129)
(0.07)
4,657
4,759
4.22
4.10
(295)
(0.06)
6,202
5,842
4.46
4.26**
(482)
(0.06)
9,596
8,265
4.76
4.42**
(783)
(0.06)
5,710
7,103
4.91
4.94
(939)
(0.10)
5,274
5,411
4.65
4.49
(389)
(0.09)
936
1,007
4.64
4.88
(98)
(0.28)
1,530
1,622
4.44
4.16
(126)
(0.15)
1,217
1,233
4.51
4.41
(177)
(0.15)
1,138
1,011
4.91
4.61
(225)
(0.16)
450
535
5.09
4.70
(162)
(0.26)
**Significant at p<0.01.
8
Del #45.1 NIS Comparison Report, 2007
Table 7. NIS and AHA Comparisons by Location and Teaching Status, 2007
Rural
Small
Medium
Large
Urban, Non-teaching
Small
Medium
Large
Urban, Teaching
Small
Medium
Large
*Significant at p<0.05.
HCUP (09/3/2010)
Number of Discharges in
Thousands
Average Length of Stay in Days
(Standard Error)
(Standard Error)
NIS
AHA
NIS
AHA
5,102
5,102
3.96
4.06
(218)
(0.06)
1,259
1,300
3.61
3.68
(61)
(0.12)
1,116
1,316*
3.59
3.78**
(100)
(0.06)
2,727
2,485
4.27
4.40
(246)
(0.09)
16,417
16,417
4.45
4.27**
(456)
(0.04)
1,923
1,922
4.33
4.42
(137)
(0.16)
4,661
4,566
4.27
4.02**
(254)
(0.07)
9,831
9,928
4.56
4.36**
(478)
(0.05)
18,021
18,021
4.92
4.75**
(618)
(0.06)
2,802
2,432
4.48
4.40
(322)
(0.11)
4,886
4,621
4.95
4.67**
(609)
(0.10)
10,332
10,967
5.03
4.86
(966)
(0.10)
**Significant at p<0.01.
9
Del #45.1 NIS Comparison Report, 2007
Summary of NIS-NHDS Comparisons
ƒ
All NIS and NHDS estimates agreed in the overall and regional comparisons.
ƒ
Agreements were also observed for most comparisons across hospital, patient,
diagnoses, and procedure categories.
ƒ
Overall, similarities between the NIS and NHDS were observed for 68% of the discharge
comparisons and 97% of the average length of stay (ALOS) comparisons.
ƒ
No significant differences were found for in-hospital mortality rates among these region
and patient categories, and estimates agreed for 53% of hospital category comparisons.
ƒ
Of the NIS-NHDS differences discovered, most occur in diagnosis and procedure
groupings.
ƒ
New to the NIS Comparison Report are tile charts that provide visual representation of
discharge estimates representing the frequency and average total charges for the 25
most common principal diagnoses (Figure 2) and procedures (Figure 3) in the NIS.
These figures represent the number of discharges for each CCS category by the size of
the rectangle, and the associated magnitude of charges by the color (green = least
expensive and orange = most expensive).
ƒ
Because of the design of the sampling frame, the NIS may over-represent urban areas.
Additionally, the prevalence of higher-density states in the NIS yields data on atypical
conditions rarely included in a smaller sample.
ƒ
When estimating ALOS and in-hospital mortality for the nation, or within any major
categories, NIS rates were consistent with the NHDS data. Because NIS estimates have
greater precision, a result of the large sample size, it may be preferred for certain
analyses based on relatively uncommon conditions. Furthermore, the NIS contains total
hospital charges, while the NHDS does not.
ƒ
Reliable estimates from the NIS are possible even for rare conditions. This is not true for
the NHDS. Because of the smaller sample size, reliable measures of ALOS and
mortality were unavailable from the NHDS for nearly all of the infrequent principal
diagnoses in Table 14.
HCUP (09/3/2010)
10
Del #45.1 NIS Comparison Report, 2007
Table 8. NIS and NHDS Comparisons by Region, 2007
Number of Discharges
in Thousands
(Standard Error)
NIS
NHDS
Overall
39,541
(799)
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
38,416
(1,751)
4.58
(0.03)
4.67
(0.34)
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
1.93
(0.02)
1.92
(0.12)
8,063
5.11
5.561
2.13
(1,096)
(0.08)
(c)
(0.06)
South
8,565
4.33
4.141
1.76
(1,017)
(0.06)
(c)
(0.04)
Midwest
14,187
4.60
4.77
1.96
(786)
(0.06)
(0.41)
(0.05)
West
7,600
4.31
4.161
1.89
(567)
(0.08)
(c)
(0.06)
*Significant at p<0.05.
**Significant at p<0.01.
1
A significance test was not performed because a valid standard error was not available.
(c) A valid standard error could not be calculated.
1.891
(c)
1.991
(c)
1.98
(0.15)
1.78
(0.18)
Region
Northeast
HCUP (09/3/2010)
7,753
(337)
9,130
(323)
15,273
(594)
7,385
(258)
11
Del #45.1 NIS Comparison Report, 2007
Table 9. NIS and NHDS Comparisons by Hospital Control, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
Total Public
1-99 Beds
100-199 Beds
200-299 Beds
300-499 Beds
500+ Beds
Total Private Non-Profit
1-99 Beds
100-199 Beds
200-299 Beds
300-499 Beds
500+ Beds
Total Proprietary
1-99 Beds
100-199 Beds
200-299 Beds
300-499 Beds
500+ Beds
*Significant at p<0.05.
HCUP (09/3/2010)
5,667
(693)
1,041
(70)
826
(130)
645
(143)
848
(243)
2,305
(383)
28,600
(965)
2,433
(129)
4,657
(295)
6,202
(482)
9,596
(783)
5,710
(939)
5,274
(389)
936
(98)
1,530
(126)
1,217
(177)
1,138
(225)
450
(162)
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
4,364
4.84
(202)
(0.16)
1,260*
3.86
(61)
(0.16)
768
4.03
(38)
(0.12)
290*
4.14
(16)
(0.16)
1,208
4.97
(58)
(0.27)
835**
5.71
(41)
(0.27)
29,174
4.53
(1,331)
(0.03)
5,695**
3.65
(262)
(0.07)
5,314
4.20
(245)
(0.07)
7,179
4.44
(330)
(0.06)
6,417**
4.74
(295)
(0.06)
4,567
4.90
(211)
(0.10)
4,877
4.63
(225)
(0.09)
1,183*
4.61
(57)
(0.28)
2,284**
4.42
(107)
(0.15)
635**
4.49
(32)
(0.15)
665*
4.90
(33)
(0.16)
108*
5.07
(7)
(0.25)
**Significant at p<0.01.
12
4.94
(0.36)
3.88
(0.29)
4.09
(0.31)
5.32*
(0.44)
5.67
(0.42)
6.11
(0.46)
4.54
(0.33)
3.85
(0.28)
4.26
(0.31)
4.53
(0.33)
4.73
(0.34)
5.46
(0.40)
5.25
(0.38)
6.91**
(0.52)
4.78
(0.35)
4.84
(0.37)
4.44
(0.34)
4.52
(0.45)
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
1.93
(0.07)
2.06
(0.07)
1.97
(0.13)
1.65
(0.23)
1.83
(0.13)
1.96
(0.13)
1.93
(0.03)
1.97
(0.06)
1.95
(0.06)
1.86
(0.05)
2.01
(0.07)
1.81
(0.09)
1.97
(0.06)
2.13
(0.18)
1.95
(0.12)
2.01
(0.09)
1.82
(0.10)
1.98
(0.24)
1.86
(0.12)
2.05
(0.14)
1.60*
(0.11)
2.78**
(0.22)
2.26*
(0.15)
0.93**
(0.06)
1.99
(0.12)
2.00
(0.13)
1.80
(0.11)
1.98
(0.12)
1.98
(0.12)
2.26*
(0.14)
1.55**
(0.10)
0.89**
(0.06)
1.55*
(0.10)
2.40
(0.17)
2.04
(0.14)
0.66**
(0.06)
Del #45.1 NIS Comparison Report, 2007
Table 10. NIS and NHDS Comparisons by Patient Characteristics, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
Age Group
0-15 Years
6,387
(241)
10,749
(294)
9,134
(200)
13,229
(273)
6,391
(294)
10,408
(477)
8,753
(402)
12,863
(589)
3.67
(0.07)
3.62
(0.04)
4.97
(0.04)
5.54
(0.04)
3.92
(0.28)
3.68
(0.26)
5.11
(0.37)
5.56
(0.40)
0.39
(0.02)
0.38
(0.01)
1.74
(0.03)
4.07
(0.05)
0.46
(0.03)
0.37
(0.02)
1.63
(0.10)
4.10
(0.26)
23,202
(492)
16,230
(324)
22,478
(1,026)
15,937
(728)
4.33
(0.03)
4.95
(0.04)
4.43
(0.32)
5.02
(0.36)
1.64
(0.02)
2.36
(0.03)
1.75
(0.11)
2.17
(0.14)
22,620*
4.69
4.71
2.22
(0.03)
(1,477)
(0.03)
(0.47)
Black
4,779
5.22
5.33
1.83
(0.05)
(334)
(0.08)
(0.59)
Other
1.35
1,508**
4.35
4.541
(c)
(0.04)
(207)
(0.09)
Unknown
1.80
9,507
4.29
4.291
(c)
(0.05)
(1,238)
(0.06)
*Significant at p<0.05.
**Significant at p<0.01.
1
A significance test was not performed because a valid standard error was not available.
(c) A valid standard error could not be calculated.
2.02
(0.18)
1.97
(0.19)
1.511
(c)
1.731
(c)
16-44 Years
45-64 Years
65+ Years
Gender
Female
Male
Race
White
HCUP (09/3/2010)
18,459
(672)
4,138
(312)
5,912
(387)
11,031
(799)
13
Del #45.1 NIS Comparison Report, 2007
Table 11. NIS and NHDS Comparisons by Principal Payer, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
Medicare
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
13,277
5.62
5.72
3.56
(678)
(0.04)
(0.44)
(0.04)
Medicaid
7,589
4.33
4.621
0.80
(603)
(0.08)
(c)
(0.02)
Private Insurance
13,280
3.76
3.83
1.00
(768)
(0.03)
(0.36)
(0.03)
Self Pay
1,737*
3.89
3.72
1.25
(109)
(0.07)
(0.39)
(0.05)
No Charge
94
4.91
4.351
1.21
(18)
(0.48)
(c)
(0.15)
Other
2,436*
4.45
4.441
1.69
(461)
(0.10)
(c)
(0.12)
Missing
01
4.18
0.001
1.61
(a)
(0.26)
(a)
(0.23)
*Significant at p<0.05.
**Significant at p<0.01.
1
A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were unreliable and
not reported.
(c) A valid standard error could not be calculated.
HCUP (09/3/2010)
14,381
(294)
7,663
(301)
13,719
(459)
2,104
(106)
205
(53)
1,383
(92)
41
(16)
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
14
3.57
(0.25)
0.81
(0.09)
1.00
(0.08)
1.39
(0.12)
1.801
(c)
1.821
(c)
0.001
(a)
Del #45.1 NIS Comparison Report, 2007
Figure 2. Discharge Estimates for the 25 Most Common Principal Diagnoses, NIS, 2007
2
50
55
100
101
102
106
108
109
AverageTotal
Charge
$57,607
$26,308
$15,488
$54,714
$46,842
$14,854
$27,964
$31,730
$39,621
Discharge
Estim ate
134,019
101,574
103,450
122,764
192,378
157,578
145,474
203,354
104,005
122
127
149
159
181
189
193
195
197
203
205
218
237
238
254
657
$25,652
$20,890
$30,265
$18,513
$10,411
$13,114
$8,420
$11,946
$18,205
$41,518
$41,140
$8,642
$49,275
$33,896
$31,590
$14,382
232,808
118,110
91,077
106,450
107,026
114,254
173,297
162,915
120,667
165,657
129,443
903,719
124,544
95,530
88,039
155,154
DXCCS
HCUP (09/3/2010)
Diagnosis
Septicemia (except in labor)
Diabetes mellitus w ith complications
Fluid and electrolyte disorders
Acute myocardial infarction
Coronary atherosclerosis and other heart disease
Nonspecific chest pain
Cardiac dysrhythmias
Congestive heart failure; nonhypertensive
Acute cerebrovascular disease
Pneumonia (except caused by tuberculosis or sexually transmitted disease)
Chronic obstructive pulmonary disease and bronchiectasis
Biliary tract disease
Urinary tract infections
Other complications of pregnancy
Previous C-section
OB-related trauma to perineum and vulva
Other complications of birth; puerperium affecting management of mother
Skin and subcutaneous tissue infections
Osteoarthritis
Spondylosis; intervertebral disc disorders; other back problems
Liveborn
Complication of device; implant or graft
Complications of surgical procedures or medical care
Rehabilitation care; fitting of prostheses; and adjustment of devices
Mood disorders
15
Del #45.1 NIS Comparison Report, 2007
Table 12. NIS and NHDS Comparisons by the 25 Most Common Principal Diagnoses, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
218: Liveborn
122: Pneumonia (except
that caused by tuberculosis
or sexually transmitted
disease)
108: Congestive heart
failure; nonhypertensive
101: Coronary
atherosclerosis and other
heart disease
193: OB-related trauma to
perineum and vulva
203: Osteoarthritis
195: Other complications of
birth; puerperium affecting
management of mother
102: Nonspecific chest pain
657: Mood Disorders
106: Cardiac dysrhythmias
2: Septicemia (except in
labor)
205: Spondylosis;
intervertebral disc
disorders; other back
problems
100: Acute myocardial
infarction
237: Complication of
device; implant or graft
197: Skin and
subcutaneous tissue
infections
127: Chronic obstructive
pulmonary disease and
bronchiectasis
189: Previous C-section
159: Urinary tract infections
HCUP (09/3/2010)
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
4,542
(180)
1,171
(21)
4,051
(188)
1,072
(52)
3.35
(0.06)
5.41
(0.04)
3.46
(0.25)
5.04
(0.38)
0.33
(0.01)
3.52
(0.07)
0.41*
(0.02)
3.71
(0.25)
1,024
(23)
963
(40)
1,023
(50)
968
(47)
5.26
(0.04)
3.31
(0.04)
5.10
(0.38)
3.22
(0.24)
3.31
(0.06)
0.51
(0.01)
2.91
(0.20)
0.58
(0.04)
867
(48)
814
(37)
810
(33)
--1
(a)
718
(36)
71**
(5)
2.08
(0.01)
3.52
(0.04)
2.79
(0.03)
--1
(a)
3.67
(0.28)
3.92*
(0.44)
0.00
(0.00)
0.09
(0.00)
0.02
(0.00)
--1
(a)
0.06**
(0.00)
0.20**
(0.02)
788
(28)
774
(44)
731
(19)
675
(17)
633
(25)
31**
(3)
1,070**
(52)
807
(40)
596*
(30)
609
(31)
1.87
(0.01)
6.89
(0.18)
3.45
(0.03)
9.05
(0.11)
3.01
(0.04)
1.711
(c)
7.00
(0.53)
3.56
(0.27)
9.32
(0.72)
3.46
(0.27)
0.06
(0.00)
0.03
(0.00)
0.97
(0.03)
17.26
(0.25)
0.15
(0.01)
0.001
(c)
0.07**
(0.00)
1.24**
(0.08)
18.53
(1.34)
0.24**
(0.01)
624
(21)
623
(20)
604
(13)
577
(29)
547*
(28)
569
(29)
5.03
(0.05)
5.99
(0.07)
4.51
(0.03)
5.09
(0.40)
5.95
(0.46)
4.46
(0.35)
6.13
(0.10)
1.66
(0.05)
0.35
(0.02)
6.68
(0.48)
1.73
(0.12)
0.30
(0.02)
593
(13)
648
(33)
4.67
(0.04)
4.42
(0.34)
1.79
(0.05)
1.55
(0.11)
561
(23)
535
(11)
--1
(a)
669**
(34)
2.85
(0.02)
4.38
(0.03)
--1
(a)
4.42
(0.34)
0.00
(0.00)
0.99
(0.03)
--1
(a)
1.23*
(0.08)
16
Del #45.1 NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
181: Other complications of
pregnancy
109: Acute cerebrovascular
disease
55: Fluid and electrolyte
disorders
50: Diabetes mellitus with
complications
238: Complications of
surgical procedures or
medical care
149: Biliary tract disease
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
531
(19)
527
(13)
519
(11)
510
(11)
481
(12)
181**
(11)
486
(25)
753**
(37)
500
(26)
478
(25)
2.41
(0.01)
6.16
(0.09)
3.59
(0.03)
5.15
(0.05)
6.13
(0.07)
2.37
(0.22)
6.26
(0.49)
3.64
(0.28)
5.62
(0.44)
6.25
(0.49)
0.03
(0.00)
9.34
(0.19)
1.63
(0.05)
0.79
(0.03)
1.32
(0.04)
0.00**
(0.00)
9.22
(0.68)
1.81
(0.12)
0.73
(0.05)
0.91**
(0.06)
454
(10)
438
(29)
419
(22)
397
(21)
4.17
(0.03)
12.85
(0.22)
3.96
(0.32)
12.88
(1.02)
0.67
(0.02)
0.62
(0.06)
0.48**
(0.03)
0.11**
(0.00)
254: Rehabilitation care;
fitting of prostheses; and
adjustment of devices
*Significant at p<0.05.
**Significant at p<0.01.
1
A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were unreliable and
not reported.
(c) A valid standard error could not be calculated.
HCUP (09/3/2010)
17
Del #45.1 NIS Comparison Report, 2007
Figure 3. Discharge Estimates for the 25 Most Common Principal Procedures, NIS, 2007
PRCCS
45
47
Average Total
Charge
$51,812
$31,275
48
54
58
61
70
76
78
80
84
115
124
134
137
140
146
152
153
158
216
219
222
228
231
$75,902
$45,726
$28,277
$74,813
$27,900
$26,472
$65,266
$24,639
$35,414
$5,980
$21,738
$15,889
$8,803
$8,210
$42,567
$42,474
$48,035
$74,954
$74,120
$12,067
$27,836
$5,156
$23,007
HCUP (09/3/2010)
2007 Discharge
Estim ate
Procedure
133,318 Percutaneous transluminal coronary angioplasty (PTCA)
115,223 Diagnostic cardiac catheterization; coronary arteriography
Insertion; revision; replacement; removal of cardiac pacemaker or
65,747 cardioverter/defibrillator
111,687 Other vascular catheterization; not heart
68,227 Hemodialysis
60,432 Other OR procedures on vessels other than head and neck
136,794 Upper gastrointestinal endoscopy; biopsy
48,963 Colonoscopy and biopsy
56,830 Colorectal resection
60,270 Appendectomy
76,864 Cholecystectomy and common duct exploration
242,709 Circumcision
104,260 Hysterectomy; abdominal and vaginal
298,240 Cesarean section
335,883 Other procedures to assist delivery
141,680 Repair of current obstetric laceration
53,409 Treatment; fracture or dislocation of hip and femur
123,019 Arthroplasty knee
81,268 Hip replacement; total and partial
72,106 Spinal fusion
149,183 Respiratory intubation and mechanical ventilation
67,587 Alcohol and drug rehabilitation/detoxification
136,708 Blood transfusion
199,108 Prophylactic vaccinations and inoculations
122,996 Other therapeutic procedures
18
Del #45.1 NIS Comparison Report, 2007
Table 13. NIS and NHDS Comparisons by the 25 Most Common Principal Procedures,
2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
137: Other procedures to
assist delivery
134: Cesarean section
115: Circumcision
228: Prophylactic
vaccinations and
inoculations
216: Respiratory intubation
and mechanical ventilation
140: Repair of current
obstetric laceration
222: Blood transfusion
70: Upper gastrointestinal
endoscopy; biopsy
45: Percutaneous
transluminal coronary
angioplasty (PTCA)
231: Other therapeutic
procedures
152: Arthroplasty knee
47: Diagnostic cardiac
catheterization; coronary
arteriography
54: Other vascular
catheterization; not heart
124: Hysterectomy;
abdominal and vaginal
153: Hip replacement; total
and partial
84: Cholecystectomy and
common duct exploration
158: Spinal fusion
219: Alcohol and drug
rehabilitation/detoxification
58: Hemodialysis
HCUP (09/3/2010)
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
1,677
(84)
1,479
(64)
1,238
(55)
1,025
(105)
1,150**
(56)
1,336
(64)
1,147
(55)
922
(45)
2.15
(0.02)
3.61
(0.04)
3.03
(0.04)
2.58
(0.04)
2.15
(0.16)
3.49
(0.26)
2.99
(0.22)
2.55
(0.19)
0.00
(0.00)
0.01
(0.00)
0.00
(0.00)
0.02
(0.00)
0.00*
(0.00)
0.01
(0.00)
0.07**
(0.00)
0.08**
(0.00)
754
(18)
708
(41)
694
(22)
685
(16)
668
(36)
671*
(34)
770
(38)
615*
(31)
653
(33)
557*
(28)
10.57
(0.18)
2.18
(0.01)
5.62
(0.05)
5.27
(0.04)
2.70
(0.04)
9.82
(0.75)
2.19
(0.17)
5.68
(0.44)
5.26
(0.41)
2.72
(0.21)
25.18
(0.34)
0.00
(0.00)
4.18
(0.09)
1.24
(0.03)
0.80
(0.03)
24.28
(1.74)
0.00
(0.00)
4.49
(0.32)
0.95**
(0.06)
0.70
(0.05)
637
(61)
605
(26)
576
(22)
570
(29)
554
(28)
512
(26)
5.10
(0.12)
3.62
(0.04)
3.59
(0.04)
5.21
(0.41)
3.54
(0.28)
3.75
(0.30)
2.62
(0.19)
0.08
(0.00)
0.81
(0.04)
3.59**
(0.26)
0.24**
(0.01)
1.09**
(0.08)
558
(18)
516
(17)
402
(17)
382
(9)
350
(18)
346
(35)
343
(13)
520
(27)
498
(26)
372
(20)
357
(19)
339
(18)
336
(18)
337
(18)
8.89
(0.12)
2.58
(0.04)
4.64
(0.05)
4.62
(0.04)
3.91
(0.09)
5.55
(0.43)
5.35
(0.09)
8.66
(0.67)
2.42
(0.19)
4.60
(0.37)
4.56
(0.37)
4.13
(0.34)
5.05
(0.41)
5.15
(0.42)
6.99
(0.14)
0.07
(0.00)
0.83
(0.04)
0.65
(0.03)
0.23
(0.02)
0.12
(0.02)
2.69
(0.09)
6.72
(0.49)
0.05*
(0.00)
0.74
(0.05)
0.78
(0.06)
0.09**
(0.00)
0.28**
(0.02)
2.72
(0.21)
19
Del #45.1 NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
NHDS
48: Insertion; revision;
replacement; removal of
cardiac pacemaker or
cardioverter/defibrillator
61: Other OR procedures
on vessels other than head
and neck
80: Appendectomy
78: Colorectal resection
146: Treatment; fracture or
dislocation of hip and femur
76: Colonoscopy and
biopsy
* Significant at p<0.05.
HCUP (09/3/2010)
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
329
(13)
273**
(15)
4.63
(0.07)
4.77
(0.40)
0.89
(0.04)
1.13*
(0.09)
305
(10)
260*
(15)
8.71
(0.26)
8.81
(0.73)
3.75
(0.12)
3.68
(0.30)
303
2.74
(17)
(0.03)
250*
9.77
(14)
(0.08)
269
6.07
(15)
(0.07)
226
5.39
(13)
(0.04)
** Significant at p<0.01.
2.77
(0.23)
9.43
(0.79)
5.99
(0.50)
5.16
(0.44)
0.11
(0.01)
3.72
(0.10)
1.60
(0.06)
0.74
(0.04)
0.21**
(0.01)
2.90**
(0.24)
1.81
(0.14)
0.75
(0.06)
300
(8)
287
(7)
269
(6)
246
(5)
20
Del #45.1 NIS Comparison Report, 2007
Table 14. NIS and NHDS Comparisons by Infrequent Principal Diagnoses, 2007
Number of
Discharges
(Standard Error)
NIS
NHDS
1: Tuberculosis
11: Cancer of head and
neck
12: Cancer of esophagus
123: Influenza
13: Cancer of stomach
148: Peritonitis and
intestinal abscess
15: Cancer of rectum and
anus
16: Cancer of liver and
intrahepatic bile duct
17: Cancer of pancreas
21: Cancer of bone and
connective tissue
227: Spinal cord injury
240: Burns
243: Poisoning by
nonmedicinal substances
25: Cancer of uterus
26: Cancer of cervix
27: Cancer of ovary
30: Cancer of testis
32: Cancer of bladder
35: Cancer of brain and
nervous system
36: Cancer of thyroid
37: Hodgkin`s disease
39: Leukemias
60: Acute posthemorrhagic
anemia
HCUP (09/3/2010)
8
(0)
32
(3)
13
(0)
17
(0)
25
(1)
27
(0)
47
(2)
20
(1)
35
(1)
17
(2)
13
(0)
27
(4)
19
(0)
41
(2)
23
(1)
25
(1)
2
(0)
38
(2)
37
(3)
29
(2)
5
(0)
43
(3)
14
(0)
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
11
(2)
29
(3)
8**
(1)
23
(3)
17*
(2)
37*
(3)
37*
(3)
17
(2)
35
(3)
11
(2)
8*
(1)
78**
(6)
18
(2)
30*
(3)
20
(2)
25
(3)
--1
(a)
34
(3)
33
(3)
25
(3)
7
(1)
56*
(5)
65**
(5)
21
15.66
(1.15)
7.67
(0.19)
9.44
(0.29)
3.74
(0.10)
10.55
(0.21)
7.90
(0.12)
8.58
(0.11)
6.49
(0.17)
8.51
(0.14)
7.52
(0.29)
14.01
(0.61)
8.75
(0.51)
3.32
(0.11)
4.19
(0.10)
3.55
(0.09)
6.76
(0.15)
6.31
(0.39)
6.23
(0.18)
7.08
(0.19)
2.29
(0.07)
11.16
(0.95)
15.07
(0.72)
3.50
(0.08)
7.491
(c)
6.221
(c)
10.721
(c)
4.091
(c)
8.701
(c)
7.961
(c)
7.881
(c)
7.651
(c)
8.131
(c)
6.021
(c)
11.511
(c)
6.81*
(0.72)
3.631
(c)
4.151
(c)
3.661
(c)
6.001
(c)
--1
(a)
5.481
(c)
7.561
(c)
1.811
(c)
5.061
(c)
10.96**
(1.23)
8.16**
(0.90)
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
3.38
(0.49)
3.77
(0.39)
9.54
(0.76)
1.07
(0.20)
8.27
(0.51)
4.05
(0.25)
3.08
(0.21)
12.38
(0.93)
10.25
(0.48)
3.22
(0.47)
5.57
(0.45)
3.17
(0.37)
1.58
(0.23)
1.26
(0.14)
1.60
(0.18)
4.48
(0.38)
2.38
(0.79)
3.13
(0.22)
3.88
(0.30)
0.66
(0.10)
4.75
(0.63)
13.52
(0.63)
0.93
(0.17)
0.651
(c)
6.591
(c)
11.011
(c)
0.531
(c)
11.901
(c)
1.771
(c)
3.571
(c)
15.171
(c)
9.531
(c)
4.671
(c)
4.721
(c)
2.10*
(0.23)
2.131
(c)
1.351
(c)
0.791
(c)
3.971
(c)
--1
(a)
1.791
(c)
5.341
(c)
0.191
(c)
1.951
(c)
13.24
(1.69)
0.07**
(0.00)
Del #45.1 NIS Comparison Report, 2007
Number of
Discharges
(Standard Error)
NIS
NHDS
Average Length of
Stay in Days
(Standard Error)
NIS
NHDS
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
NHDS
76: Meningitis (except that
42
42
5.03
5.041
1.45
caused by tuberculosis or
(1)
(4)
(0.09)
(c)
(0.13)
sexually transmitted
disease)
77: Encephalitis (except
9
10
9.57
9.541
3.66
that caused by tuberculosis
(0)
(1)
(0.31)
(c)
(0.43)
or sexually transmitted
disease)
* Significant at p<0.05.
** Significant at p<0.01.
1
A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were
unreliable and not reported.
(b) The NHDS estimate was reported but is not considered reliable; the standard error was
not reported.
(c) A valid standard error could not be calculated.
HCUP (09/3/2010)
22
0.481
(c)
7.551
(c)
Del #45.1 NIS Comparison Report, 2007
Summary of NIS-MedPAR Comparisons
ƒ
With the exception of discharge counts, NIS estimates of Medicare measures were
generally consistent with MedPAR statistics.
ƒ
NIS discharge estimates were uniformly higher than the MedPAR numbers by
approximately 11%, consistent with the omission of most managed care enrollees from
the MedPAR. While 19.0% of Medicare patients were enrolled in managed care
programs, the MedPAR data contain a very small number of managed care discharges
(only 3.16% of 13,306,427 total discharges).
ƒ
The NIS provides a large sample of Medicare discharges both in managed care and feefor-service plans; it would therefore, be the choice of researchers who wished to include
all discharges regardless of payment type. Inclusion of Medicare managed care
discharges leads to discrepancies in estimated discharge counts, but most other NIS
Medicare estimates were similar to MedPAR statistics, particularly with respect to
comparisons by hospital characteristics.
ƒ
The NIS contains significant numbers of discharges for which race was missing (26
percent). While the NHDS also suffers from this problem (25% of discharges without
race), race information is present for nearly all MedPAR discharges.
ƒ
New to the NIS Comparison Report are tile charts that provide visual representation of
discharge estimates representing the frequency and average total charges for the most
frequent diagnosis-related groups (DRG) (Figure 4), principal diagnoses (Figure 5), and
procedures (Figure 6) among the Medicare population in the NIS.
HCUP (09/3/2010)
23
Del #45.1 NIS Comparison Report, 2007
Table 15. NIS and MedPAR Comparisons by Region, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
U.S.
14,381
(293)
12,912**
2,939
(148)
3,545
(131)
5,620
(195)
2,276
(92)
2,554**
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
n/a
Average Length of
Stay in Days
(Standard Error)
NIS
MedPAR
n/a
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
5.63
(0.04)
5.80**
3.56
(0.04)
3.51
$32,752
(689)
$32,794
6.29
(0.10)
5.18
(0.06)
5.65
(0.06)
5.45
(0.10)
6.42
4.12
(0.11)
3.06
(0.07)
3.48
(0.06)
3.81
(0.11)
3.85*
$34,985
(1,947)
$25,899
(830)
$29,865
(816)
$48,668
(2,577)
$36,837
Region
Northeast
South
Midwest
West
*Significant at p<0.05.
HCUP (9/3/2010)
3,503
5,053**
1,800**
20.43
19.78
(0.89)
24.65
27.13**
(0.82)
39.08
39.13
(1.02)
15.82
13.94**
(0.62)
**Significant at p<0.01.
24
5.35**
5.89**
5.50
3.12
3.54
3.75
$26,705
$30,575
$45,135
Del #45.1: NIS Comparison Report, 2007
Table 16. NIS and MedPAR Comparisons by Hospital Control, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
Total Public
1-99 Beds
100-199
Beds
200-299
Beds
300-499
Beds
500+ Beds
Total Private
Non-Profit
1-99 Beds
100-199
Beds
200-299
Beds
300-499
Beds
500+ Beds
HCUP (9/3/2010)
1,817
(170)
485
(29)
297
(48)
224
(48)
235
(76)
574
(100)
10,480
(336)
1,042
(50)
1,826
(113)
2,346
(196)
3,517
(305)
1,748
(284)
1,603
431
286
197
313
373*
9,422**
1,026
1,668
1,921*
2,696**
2,109
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
12.63
(1.19)
26.72
(2.03)
16.35
(2.65)
12.35
(2.88)
12.95
(4.05)
31.61
(4.60)
72.87
(1.47)
9.94
(0.53)
17.42
(1.11)
22.39
(1.89)
33.55
(2.79)
16.67
(2.56)
Average Length of In-Hospital Mortality Average Total Hospital
Stay in Days
Rate Percent
charge
(Standard Error)
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
NIS
MedPAR
12.42
5.60
(0.14)
4.68
(0.15)
5.09
(0.15)
5.49
(0.21)
6.15
(0.36)
6.45
(0.32)
5.59
(0.04)
4.68
(0.10)
5.28
(0.07)
5.53
(0.09)
5.79
(0.08)
6.16
(0.14)
26.92
17.86
12.32
19.57
23.30
72.97
10.89
17.70
20.39
28.61
22.38*
25
5.54
4.33*
5.31
5.64
6.21
6.49
5.64
4.75
5.44*
5.54
5.73
6.21
3.64
(0.09)
3.43
(0.11)
3.95
(0.24)
3.50
(0.36)
3.60
(0.34)
3.73
(0.17)
3.58
(0.05)
3.62
(0.10)
3.66
(0.10)
3.39
(0.10)
3.60
(0.11)
3.68
(0.15)
3.58
3.15*
3.56
3.61
3.85
3.86
3.49
3.22**
3.44*
3.53
3.47
3.68
$26,698
(1,426)
$12,610
(556)
$30,170
(4,707)
$25,715
(2,058)
$33,324
(4,052)
$34,311
(2,822)
$31,741
(847)
$18,284
(883)
$26,601
(1,476)
$28,973
(1,384)
$34,709
(1,631)
$42,449
(2,677)
$27,207
$11,773
$24,187
$30,030*
$34,207
$39,981*
$31,963
$17,240
$25,949
$30,404
$34,766
$41,726
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
Total
Proprietary
1-99 Beds
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
2,083
(130)
423
(39)
1,885
100-199
Beds
669
(54)
557*
32.12
(2.42)
29.55
5.63
(0.20)
5.94
3.12
(0.17)
3.41
$41,829
(3,543)
$37,664
200-299
Beds
529
(82)
412
25.39
(3.60)
21.89
5.75
(0.26)
6.17
3.36
(0.16)
3.72*
$41,029
(3,486)
$44,081
300-499
Beds
368
(67)
294
17.68
(3.29)
15.60
5.80
(0.15)
6.26**
3.37
(0.23)
3.60
$54,077
(5,466)
$53,768
500+ Beds
93
(40)
150
4.48
(1.92)
7.95
6.30
(0.25)
6.38
3.97
(0.53)
3.68
$61,564
(3,157)
$48,342**
*Significant at p<0.05.
HCUP (9/3/2010)
471
14.48
(0.91)
20.31
(1.77)
Average Length of In-Hospital Mortality Average Total Hospital
Stay in Days
Rate Percent
charge
(Standard Error)
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
NIS
MedPAR
14.60
5.88
(0.14)
6.38
(0.47)
24.98**
6.79**
8.79**
3.38
(0.11)
3.68
(0.29)
3.55
3.50
$43,050
(2,040)
$33,721
(2,210)
$41,700
$34,735
**Significant at p<0.01.
26
Del #45.1: NIS Comparison Report, 2007
Table 17. NIS and MedPAR Comparisons by Hospital Location and Teaching Status, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
Rural
2,308
(98)
Small
641
(26)
Medium
473
(43)
Large
1,193
(110)
Urban, Non6,395
teaching
(181)
Small
801
(52)
Medium
1,891
(98)
Large
3,702
(181)
Urban,
5,676
Teaching
(208)
Small
907
(124)
Medium
1,636
(222)
Large
3,132
(293)
*Significant at p<0.05.
HCUP (9/3/2010)
2,121
561**
528
1,031
5,647**
792
1,536**
3,318*
5,143*
672
1,321
3,150
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of In-Hospital Mortality Average Total Hospital
Stay in Days
Rate Percent
charge
(Standard Error)
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
NIS
MedPAR
16.05
16.42
4.87
(0.65)
(0.07)
27.79
26.46
4.25
(1.49)
(0.09)
20.51
24.90*
4.59
(2.19)
(0.09)
51.68
48.63
5.31
(2.93)
(0.11)
44.47
43.73
5.66
(1.00)
(0.06)
12.52
14.03
5.95
(0.82)
(0.28)
29.57
27.20
5.45
(1.59)
(0.09)
57.89
58.75
5.70
(1.72)
(0.07)
39.47
39.83
5.92
(1.04)
(0.06)
15.99
13.06
5.53
(2.13)
(0.15)
28.83
25.69
5.93
(4.00)
(0.11)
55.17
61.24
6.02
(4.33)
(0.11)
**Significant at p<0.01.
27
4.76
4.08
4.57
5.23
5.94**
7.44**
5.64
5.72
6.07*
5.92*
6.02
6.12
3.56
(0.07)
3.51
(0.12)
3.45
(0.11)
3.63
(0.11)
3.53
(0.06)
3.74
(0.18)
3.54
(0.10)
3.48
(0.08)
3.59
(0.08)
3.37
(0.22)
3.74
(0.17)
3.58
(0.11)
3.36**
3.10**
3.33
3.51
3.51
3.39
3.49
3.55
3.58
3.44
3.57
3.62
$17,763
(597)
$11,240
(500)
$16,582
(705)
$21,718
(927)
$34,099
(999)
$29,107
(1,476)
$33,464
(1,989)
$35,501
(1,427)
$37,376
(1,296)
$30,418
(2,190)
$38,462
(2,873)
$38,658
(1,713)
$17,334
$10,849
$16,189
$21,449
$33,810
$29,307
$31,119
$36,131
$38,055
$32,867
$36,779
$39,698
Del #45.1: NIS Comparison Report, 2007
Table 18. NIS and MedPAR Comparisons by Patient Characteristics, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of
Stay in Days
(Standard Error)
NIS
MedPAR
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
Age Group
0-64
Years
65-74
Years
75-84
Years
85+
Years
2,601
(67)
4,187
(91)
4,842
(109)
2,747
(66)
2,382**
8,110
(164)
6,263
(132)
7,244**
8,177
(303)
1,258
(98)
1,148
(81)
3,796
(267)
10,657**
3,788**
4,152**
2,588*
18.09
(0.35)
29.11
(0.20)
33.67
(0.20)
19.10
(0.23)
18.45
29.34
32.15**
20.04**
5.92
(0.06)
5.39
(0.03)
5.67
(0.04)
5.66
(0.05)
6.15**
5.58
(0.04)
5.71
(0.04)
5.75**
5.59
(0.04)
6.51
(0.10)
6.25
(0.11)
5.25
(0.06)
5.64
5.58**
5.80**
5.79*
1.83
(0.03)
2.75
(0.03)
3.92
(0.05)
5.80
(0.08)
1.85
2.81
3.77**
5.66
$32,258
(769)
$35,552
(734)
$33,334
(706)
$27,925
(692)
$32,883
$30,845
(644)
$35,218
(754)
$30,816
$33,424
(847)
$36,841
(1,700)
$42,391
(1,628)
$27,111
(939)
$31,976
$35,938
$33,136
$27,561
Gender
Female
Male
5,667**
56.39
(0.15)
43.54
(0.15)
56.10
43.89*
5.86**
3.31
(0.04)
3.89
(0.04)
3.26
3.66
(0.05)
3.47
(0.08)
3.69
(0.11)
3.34
(0.07)
3.53*
3.83
$35,322
Race
White
Black
Other
Unknown
*Significant at p<0.05.
HCUP (9/3/2010)
1,598**
616**
39**
56.86
82.53**
(1.60)
8.75
12.38**
(0.66)
7.98
4.77**
(0.56)
26.40
0.30**
(1.82)
**Significant at p<0.01.
28
6.63
6.23
5.74**
3.42
3.60
2.62**
$34,711
$41,912
$33,533**
Del #45.1: NIS Comparison Report, 2007
Figure 4. Medicare Discharge Estimates for the 25 Most Common DRGs in the NIS, 2007
DRG
14
79
87
88
89
121
127
138
141
143
174
182
210
243
277
296
316
320
395
430
462
470
544
558
576
Average Total
Charge
$26,192
$35,398
$29,518
$18,950
$21,926
$32,258
$22,327
$17,766
$17,074
$13,211
$22,999
$17,261
$41,571
$21,582
$20,099
$17,399
$25,777
$19,051
$18,425
$20,531
$29,362
$41,898
$42,280
$44,377
$36,618
HCUP (9/3/2010)
2007 Discharge
Estim ate
45,148
29,020
21,199
68,577
86,190
23,321
107,649
38,468
23,159
41,297
42,074
47,167
21,838
19,201
22,857
42,492
49,522
41,792
22,095
50,969
47,805
23,704
79,353
20,728
56,908
Diagnosis Related Group
Intracranial Hemorrhage Or Cerebral Infarction
Respiratory Infections & Inflammations Age >17 W CC
Pulmonary Edema & Respiratory Failure
Chronic Obstructive Pulmonary Disease
Simple Pneumonia & Pleurisy Age >17 W CC
Circulatory Disorders W Ami & Major Comp, Discharged Alive
Heart Failure & Shock
Cardiac Arrhythmia & Conduction Disorders W CC
Syncope & Collapse W CC
Chest Pain
G.I. Hemorrhage W CC
Esophagitis, Gastroent & Misc Digest Disorders Age >17 W CC
Hip & Femur Procedures Except Major Joint Age >17 W CC
Medical Back Problems
Cellulitis Age >17 W CC
Nutritional & Misc Metabolic Disorders Age >17 W CC
Renal Failure
Kidney & Urinary Tract Infections Age >17 W CC
Red Blood Cell Disorders Age >17
Psychoses
Rehabilitation
Ungroupable
Major Joint Replacement Or Reattachment Of Low er Extremity
Percutaneous Cardiovascular Proc W Drug-Eluting Stent W/O Maj Cv Dx
Septicemia W/O Mv 96+ Hours Age >17
29
Del #45.1: NIS Comparison Report, 2007
Table 19. NIS and MedPAR Comparisons by DRG, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
127: Heart
Failure & Shock
89: Simple
Pneumonia &
Pleurisy Age
>17 w CC
544: Major Joint
and Limb
Reattachments
Procedures of
Lower Extremity
88: Chronic
Obstructive
Pulmonary
Disease
576: Septicemia
without
Mechanical
Ventilation
96 + Hours Age
>17
430: Psychoses
316: Renal
Failure
HCUP (9/3/2010)
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of
Stay in Days
(Standard Error)
NIS
MedPAR
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
545
(12)
626**
3.79
(0.05)
4.84**
5.00
(0.03)
5.01
3.41
(0.07)
3.38
$22,166
(578)
$21,829
437
(9)
479**
3.04
(0.04)
3.71**
5.30
(0.04)
5.29
3.58
(0.08)
3.57
$21,714
(512)
$21,324
393
(16)
461**
2.73
(0.09)
3.57**
4.19
(0.03)
4.19
0.54
(0.02)
0.56
$41,944
(839)
$41,944
346
(8)
406**
2.40
(0.04)
3.14**
4.67
(0.04)
4.71
1.28
(0.05)
1.22
$18,762
(432)
$18,977
287
(8)
335**
1.99
(0.04)
2.59**
7.11
(0.08)
7.11
17.49
(0.29)
17.25
$36,472
(944)
$35,613
256
(15)
251
(6)
329**
1.78
(0.10)
1.74
(0.03)
2.55**
10.50
(0.28)
5.72
(0.05)
10.53
0.09
(0.01)
5.31
(0.13)
0.08
$20,613
(732)
$25,551
(605)
$20,379
275**
2.13**
30
5.85*
5.31
$25,843
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
182: Esophagitis
462:
Rehabilitation
14: Intracranial
hemorrhage and
stroke with
infarction
296: Nutritional
& Misc Metabolic
Disorders Age
>17 w CC
174: G.I.
Hemorrhage w
CC
320: Kidney &
Urinary Tract
Infections Age
>17 w CC
143: Chest Pain
138: Cardiac
Arrhythmia &
Conduction
Disorders w CC
HCUP (9/3/2010)
239
(5)
237
(16)
269**
228
(5)
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of
Stay in Days
(Standard Error)
NIS
MedPAR
2.09**
271**
1.58
(0.02)
2.10**
5.11
(0.04)
5.36**
9.33
(0.23)
9.10
$26,126
(644)
$26,155
215
(4)
241**
1.49
(0.02)
1.86**
4.34
(0.03)
4.41
2.82
(0.10)
2.65
$17,273
(431)
$17,180
212
(5)
243**
1.47
(0.01)
1.88**
4.55
(0.03)
4.58
2.43
(0.07)
2.54
$22,933
(527)
$22,557
211
(5)
246**
1.47
(0.02)
1.90**
4.78
(0.04)
4.82
1.47
(0.06)
1.49
$18,971
(570)
$18,386
208
(7)
194
(4)
225*
1.45
(0.03)
1.35
(0.01)
1.74**
2.08
(0.02)
3.76
(0.03)
2.08
0.09
(0.01)
2.02
(0.08)
0.11
$13,090
(346)
$17,679
(431)
$12,733
224**
2.63**
1.74**
31
3.95
13.03**
3.79
0.77
(0.04)
0.70
(0.07)
0.78
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
1.66
(0.02)
1.65
(0.11)
339**
3.93
(0.03)
12.08
(0.17)
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
MedPAR
0.25**
2.09
$17,125
(376)
$29,202
(1,074)
$17,075
$29,673
$17,682
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
79: Respiratory
Infections &
Inflammations
Age >17 w CC
121: Circulatory
Disorders w AMI
& Major Comp
141: Syncope &
Collapse w CC
470:
Ungroupable
277: Cellulitis
Age >17 w CC
395: Red Blood
Cell Disorders
Age >17
210: Hip &
Femur
Procedures
Except Major
Joint Age >17 w
CC
87: Pulmonary
Edema &
Respiratory
Failure
HCUP (9/3/2010)
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of
Stay in Days
(Standard Error)
NIS
MedPAR
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
146
(4)
168**
1.01
(0.02)
1.30**
8.07
(0.10)
8.13
10.18
(0.23)
10.02
$35,040
(976)
$35,147
119
(3)
134**
0.83
(0.01)
1.04**
5.81
(0.05)
5.88
0.00
(0.00)
0.001
$32,147
(830)
$31,929
117
(3)
131**
0.81
(0.01)
1.01**
3.30
(0.03)
3.29
0.40
(0.04)
0.39
$16,966
(462)
$16,640
116
(5)
0**
0.80
(0.03)
0.00**
3.90
(0.04)
2.50**
0.21
(0.03)
0.00**
$41,572
(858)
$8,887**
115
(2)
133**
0.80
(0.01)
1.03**
5.39
(0.05)
5.45
0.78
(0.06)
0.77
$19,919
(543)
$19,602
112
(2)
121**
0.77
(0.01)
0.94**
3.92
(0.04)
4.04*
1.02
(0.07)
1.21*
$18,314
(465)
$18,196
110
(3)
130**
0.76
(0.01)
1.01**
6.43
(0.05)
6.45
2.11
(0.10)
2.32*
$41,365
(951)
$41,359
106
(4)
124**
0.73
(0.02)
0.96**
6.32
(0.09)
6.74**
12.06
(0.33)
11.90
$29,204
(741)
$30,927*
32
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
558:
Percutaneous
Cardiovascular
Proc w DrugEluting Stent w/o
Maj CV DX
243: Medical
Back Problems
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of
Stay in Days
(Standard Error)
NIS
MedPAR
In-Hospital Mortality
Rate Percent
(Standard Error)
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
103
(6)
119*
0.71
(0.03)
0.92**
1.82
(0.02)
1.72**
0.02
(0.01)
0.03
$44,151
(1,367)
$45,973
97
(2)
105**
0.67
(0.01)
0.81**
4.39
(0.03)
4.59**
0.89
(0.06)
0.95
$21,393
(483)
$17,633**
*Significant at p<0.05.
**Significant at p<0.01.
1
A significance test was not performed because a valid standard error was not available.
HCUP (9/3/2010)
33
Del #45.1: NIS Comparison Report, 2007
Figure 5. Medicare Discharge Estimates for the 25 Most Common Principal Diagnoses,
NIS, 2007
DXCCS
2
50
55
100
101
102
106
108
109
122
127
131
145
153
157
159
197
203
205
226
237
238
245
254
657
AverageTotal
Charge
$54,674
$30,027
$17,226
$51,813
$47,310
$15,234
$28,403
$30,243
$33,930
$27,211
$21,307
$59,343
$33,651
$26,240
$30,200
$19,828
$21,361
$41,329
$39,171
$40,596
$49,244
$37,049
$18,216
$29,436
$18,755
HCUP (9/3/2010)
Discharge
Estim ate
92,040
43,896
58,477
68,970
104,923
61,307
94,166
151,515
66,674
135,971
82,497
50,812
35,749
43,634
55,163
65,265
42,144
92,374
47,449
50,139
72,281
42,381
33,047
62,734
37,655
Diagnosis
Septicemia (except in labor)
Diabetes mellitus w ith complications
Fluid and electrolyte disorders
Acute myocardial infarction
Coronary atherosclerosis and other heart disease
Nonspecific chest pain
Cardiac dysrhythmias
Congestive heart failure; nonhypertensive
Acute cerebrovascular disease
Pneumonia (except that caused by tuberculosis or sexually transmitted disease)
Chronic obstructive pulmonary disease and bronchiectasis
Respiratory failure; insufficiency; arrest (adult)
Intestinal obstruction w ithout hernia
Gastrointestinal hemorrhage
Acute and unspecified renal failure
Urinary tract infections
Skin and subcutaneous tissue infections
Osteoarthritis
Spondylosis; intervertebral disc disorders; other back problems
Fracture of neck of femur (hip)
Complication of device; implant or graft
Complications of surgical procedures or medical care
Syncope
Rehabilitation care; fitting of prostheses; and adjustment of devices
Mood disorders
34
Del #45.1: NIS Comparison Report, 2007
Table 20. NIS and MedPAR Comparisons by the 25 Most Common Principal Diagnoses, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
108: Congestive
heart failure;
nonhypertensive
122: Pneumonia
(except that
caused by
tuberculosis or
sexually
transmitted
disease)
101: Coronary
atherosclerosis
and other heart
disease
106: Cardiac
dysrhythmias
2: Septicemia
(except in labor)
203:
Osteoarthritis
127: Chronic
obstructive
pulmonary
disease and
bronchiectasis
237: Complication
of device; implant
or graft
HCUP (9/3/2010)
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of In-Hospital Mortality
Stay in Days
Rate Percent
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
764
(17)
677**
5.31
(0.06)
5.24
5.31
(0.04)
5.39
3.55
(0.06)
3.62
$30,103
(801)
$30,279
687
(13)
597**
4.78
(0.06)
4.62*
5.96
(0.05)
5.98
4.78
(0.09)
4.70
$26,983
(706)
$26,446
525
(23)
481
3.65
(0.13)
3.72
3.55
(0.04)
3.59
0.71
(0.02)
0.73
$47,057
(1,329)
$47,671
473
(13)
463
(13)
454
(20)
414
(9)
423**
3.29
(0.04)
3.22
(0.07)
3.16
(0.12)
2.88
(0.04)
3.27
3.75
(0.03)
8.98
(0.13)
3.67
(0.03)
4.89
(0.04)
3.78
1.20
(0.04)
18.85
(0.29)
0.12
(0.01)
1.98
(0.06)
1.23
$28,348
(635)
$54,700
(1,631)
$40,983
(837)
$21,125
(497)
$28,510
362
(11)
340
402**
413*
366**
2.51
(0.05)
3.12
3.20
2.83
2.63*
6.20
(0.07)
35
8.94
3.72
4.94
6.24
2.01
(0.06)
18.72
0.12
1.92
2.09
$49,066
(1,351)
$53,188
$40,234
$21,180
$48,870
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
100: Acute
myocardial
infarction
109: Acute
cerebrovascular
disease
159: Urinary tract
infections
254:
Rehabilitation
care; fitting of
prostheses; and
adjustment of
devices
102: Nonspecific
chest pain
55: Fluid and
electrolyte
disorders
157: Acute and
unspecified renal
failure
131: Respiratory
failure;
insufficiency;
arrest (adult)
226: Fracture of
neck of femur
(hip)
205: Spondylosis;
intervertebral disc
disorders; other
back problems
HCUP (9/3/2010)
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of In-Hospital Mortality
Stay in Days
Rate Percent
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
351
(11)
314**
2.44
(0.05)
2.43
5.63
(0.05)
5.68
8.39
(0.14)
8.36
$51,614
(1,379)
$52,361
337
(8)
306**
2.34
(0.03)
2.37
5.79
(0.06)
5.99**
9.67
(0.23)
9.51
$33,928
(1,012)
$33,516
330
(7)
311
(21)
293**
2.29
(0.03)
2.16
(0.14)
2.27
4.82
(0.04)
12.24
(0.17)
4.83
1.37
(0.05)
0.73
(0.07)
1.37
$19,753
(576)
$29,304
(1,135)
$18,882
308
(10)
294
(6)
266**
279
(7)
343
2.66**
2.14
(0.05)
2.05
(0.02)
2.06
239**
1.94
(0.03)
254
(7)
230**
252
(6)
234
(8)
13.09**
2.18
(0.02)
4.10
(0.03)
2.19
1.85*
6.41
(0.06)
1.76
(0.04)
1.78
226**
1.75
(0.02)
224
1.62
(0.04)
263**
0.26**
0.11
(0.01)
2.13
(0.07)
0.12
6.49
5.76
(0.13)
9.37
(0.18)
10.17**
1.75
6.17
(0.05)
1.73*
3.69
(0.04)
2.04
36
$30,029
$15,099
(375)
$17,109
(436)
$14,737
5.81
$29,990
(791)
$29,816
18.65
(0.34)
18.70
$58,948
(1,818)
$61,588
6.28*
2.81
(0.08)
2.84
$40,384
(865)
$39,481
3.73
0.29
(0.02)
0.29
$38,799
(1,047)
$37,743
4.13
2.20
$16,703
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
50: Diabetes
mellitus with
complications
153:
Gastrointestinal
hemorrhage
238:
Complications of
surgical
procedures or
medical care
197: Skin and
subcutaneous
tissue infections
657: Mood
Disorders
145: Intestinal
obstruction
without hernia
245: Syncope
*Significant at p<0.05.
HCUP (9/3/2010)
Percentage of
Discharges
(Standard Error)
NIS
MedPAR
Average Length of In-Hospital Mortality
Stay in Days
Rate Percent
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
221
(5)
195**
1.54
(0.02)
1.51
5.95
(0.07)
6.16**
1.30
(0.05)
1.30
$29,763
(791)
$30,621
219
(5)
192**
1.52
(0.01)
1.49
4.82
(0.04)
4.79
3.42
(0.09)
3.38
$26,148
(614)
$25,196
213
(5)
192**
1.48
(0.02)
1.48
6.87
(0.09)
7.13**
2.06
(0.07)
2.12
$36,841
(1,055)
$37,112
212
(4)
188**
1.47
(0.01)
1.46
5.45
(0.05)
5.49
0.72
(0.04)
0.70
$21,164
(542)
$20,422
189
(10)
179
(4)
188
1.31
(0.07)
1.24
(0.01)
1.46
9.15
(0.23)
6.62
(0.05)
9.25
0.09
(0.01)
3.66
(0.11)
0.07
$18,833
(680)
$33,424
(706)
$18,378
1.16
1.10
3.04
(0.02)
(0.03)
**Significant at p<0.01.
3.03
0.31
(0.03)
0.33
$18,141
(514)
$17,510
166
(5)
159**
142**
1.23
37
6.69
3.66
$33,153
Del #45.1: NIS Comparison Report, 2007
Figure 6. Medicare Discharge Estimates for the 25 Most Common Principal Procedures,
NIS, 2007
3
37
39
44
45
47
Average Total
Charge
$29,596
$48,679
$38,281
$118,164
$51,499
$32,807
2007 Discharge
Estim ate
16,875
17,099
22,188
20,227
66,848
56,162
48
51
54
58
61
70
76
78
84
146
152
153
158
169
193
213
216
222
231
$71,967
$28,640
$43,968
$28,181
$62,243
$29,265
$27,776
$71,850
$44,194
$40,344
$42,873
$48,276
$80,053
$55,958
$27,096
$28,718
$67,319
$27,574
$26,456
48,558
16,964
58,937
50,699
38,245
74,896
27,487
27,871
24,934
36,555
68,431
49,979
20,601
18,993
26,970
18,822
71,602
86,521
43,363
PRCCS
HCUP (9/3/2010)
Label
Laminectomy; excision intervertebral disc
Diagnostic bronchoscopy and biopsy of bronchus
Incision of pleura; thoracentesis; chest drainage
Coronary artery bypass graft (CABG)
Percutaneous transluminal coronary angioplasty (PTCA)
Diagnostic cardiac catheterization; coronary arteriography
Insertion; revision; replacement; removal of cardiac pacemaker or
cardioverter/defibrillator
Endarterectomy; vessel of head and neck
Other vascular catheterization; not heart
Hemodialysis
Other OR procedures on vessels other than head and neck
Upper gastrointestinal endoscopy; biopsy
Colonoscopy and biopsy
Colorectal resection
Cholecystectomy and common duct exploration
Treatment; fracture or dislocation of hip and femur
Arthroplasty knee
Hip replacement; total and partial
Spinal fusion
Debridement of w ound; infection or burn
Diagnostic ultrasound of heart (echocardiogram)
Physical therapy exercises; manipulation; and other procedures
Respiratory intubation and mechanical ventilation
Blood transfusion
Other therapeutic procedures
38
Del #45.1: NIS Comparison Report, 2007
Table 21. NIS and MedPAR Comparisons by the 25 Most Common Principal Procedures, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
222: Blood transfusion
70: Upper gastrointestinal
endoscopy; biopsy
216: Respiratory
intubation and
mechanical ventilation
152: Arthroplasty knee
45: Percutaneous
transluminal coronary
angioplasty (PTCA)
54: Other vascular
catheterization; not heart
47: Diagnostic cardiac
catheterization; coronary
arteriography
58: Hemodialysis
153: Hip replacement;
total and partial
48: Insertion; revision;
replacement; removal of
cardiac pacemaker or
cardioverter/defibrillator
231: Other therapeutic
procedures
61: Other OR procedures
on vessels other than
head and neck
HCUP (9/3/2010)
441
(14)
375
(9)
362
(9)
374**
336
(15)
334
(19)
305*
294
(10)
281
(11)
273*
254
(8)
248
(9)
243
(10)
234*
226
(27)
192
(7)
338**
314**
321
257
221**
216*
166*
174*
Percentage of
Average Length of
Discharges
Stay in Days
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
3.06
(0.08)
2.61
(0.04)
2.52
(0.04)
2.89*
2.34
(0.09)
2.32
(0.11)
2.36
2.04
(0.05)
1.95
(0.06)
2.11
1.77
(0.05)
1.72
(0.05)
1.69
(0.05)
1.81
1.57
(0.18)
1.33
(0.03)
1.29
2.62
2.43
2.49
1.99
1.71
1.67
1.35
39
5.85
(0.06)
5.77
(0.04)
9.28
(0.12)
5.96
5.82
9.71**
3.76
(0.04)
2.93
(0.04)
3.75
8.78
(0.10)
4.06
(0.04)
8.88
5.48
(0.06)
5.10
(0.04)
4.65
(0.07)
5.63*
5.59
(0.17)
7.14
(0.15)
5.77
2.96
4.07
5.11
4.79
7.22
In-Hospital
Mortality Rate
Percent
(Standard Error)
NIS
MedPAR
4.71
(0.11)
1.62
(0.05)
33.57
(0.40)
4.87
1.55
34.26
0.12
(0.01)
1.16
(0.05)
0.12
9.57
(0.20)
1.16
(0.06)
9.77
2.91
(0.09)
1.21
(0.06)
1.01
(0.05)
2.96
5.36
(0.31)
3.65
(0.15)
1.14
1.25
1.23
1.08
5.61
3.78
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
$27,265
(689)
$29,163
(682)
$66,824
(1,970)
$27,013
$42,523
(874)
$51,215
(1,534)
$42,269
$43,592
(1,041)
$32,631
(817)
$42,802
$28,031
(813)
$47,985
(1,089)
$71,938
(1,720)
$27,913
$26,270
(1,387)
$62,148
(1,663)
$28,145
$67,606
$51,412
$32,111
$46,906
$73,147
$26,545
$62,231
Del #45.1: NIS Comparison Report, 2007
Number of
Discharges in
Thousands
(Standard Error)
NIS
MedPAR
146: Treatment; fracture
or dislocation of hip and
femur
78: Colorectal resection
76: Colonoscopy and
biopsy
193: Diagnostic
ultrasound of heart
(echocardiogram)
84: Cholecystectomy and
common duct exploration
39: Incision of pleura;
thoracentesis; chest
drainage
44: Coronary artery
bypass graft (CABG)
158: Spinal fusion
169: Debridement of
wound; infection or burn
213: Physical therapy
exercises; manipulation;
and other procedures
37: Diagnostic
bronchoscopy and biopsy
of bronchus
51: Endarterectomy;
vessel of head and neck
3: Laminectomy; excision
intervertebral disc
*Significant at p<0.05.
HCUP (9/3/2010)
Percentage of
Average Length of
Discharges
Stay in Days
(Standard Error)
(Standard Error)
NIS
MedPAR
NIS
MedPAR
In-Hospital
Mortality Rate
Percent
(Standard Error)
NIS
MedPAR
Average Total
Hospital charge
(Standard Error)
NIS
MedPAR
184
(4)
164**
1.28
(0.02)
1.27
6.14
(0.05)
6.17
1.95
(0.08)
2.12*
$40,187
(898)
$39,672
140
(4)
138
(3)
137
(15)
123**
0.97
(0.01)
0.96
(0.01)
0.95
(0.10)
0.95
10.76
(0.09)
5.85
(0.05)
5.14
(0.09)
10.91
5.78
(0.16)
1.06
(0.06)
2.18
(0.13)
6.03
$71,303
(1,534)
$27,685
(707)
$26,920
(1,547)
$71,806
124
(3)
111
(2)
114**
0.86
(0.01)
0.77
(0.01)
0.88
6.23
(0.06)
7.86
(0.07)
6.28
1.56
(0.08)
7.02
(0.19)
1.55
$43,840
(943)
$38,050
(991)
$43,333
102
(6)
100
(5)
95
(2)
93
(12)
97
0.70
(0.03)
0.70
(0.03)
0.66
(0.01)
0.65
(0.08)
0.75
10.19
(0.14)
4.63
(0.10)
11.75
(0.29)
11.35
(0.51)
10.06
2.67
(0.12)
0.49
(0.05)
3.86
(0.20)
0.88
(0.16)
2.73
117,412
(3,762)
$79,688
(2,419)
$55,523
(2,032)
$28,505
(2,080)
115,644
8.98
(0.11)
8.98
5.34
(0.21)
5.39
$48,471
(1,524)
$47,726
2.60
(0.06)
3.33
(0.07)
2.65
0.40
(0.04)
0.33
(0.05)
0.35
$28,678
(871)
$29,741
(1,090)
$28,046
122**
125
99**
103
90
82
85
(3)
79
84
(3)
82
(4)
71**
0.59
(0.01)
0.94
0.97
0.77
0.80**
0.70*
0.63
0.61
0.58
0.55
(0.02)
77
0.57
0.59
(0.02)
**Significant at p<0.01.
40
5.89
5.14
7.93
4.61
12.28
11.67
3.28
1.08
2.11
6.90
0.52
4.15
0.47*
0.28
$26,816
$25,190
$37,726
$76,626
$56,069
$33,237*
$28,353
Del #45.1: NIS Comparison Report, 2007
REFERENCES
National Center for Health Statistics (2010). National Hospital Discharge Survey 2007 Public
Use Data File Documentation. Washington, DC: U.S. Department of Health and Human
Services, National Center for Health Statistics.
ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHDS/ (Accessed April
28, 2010).
U.S. Agency for Healthcare Research and Quality (2010). Introduction to the NIS, 2007.
Rockville, MD.
http://www.hcup-us.ahrq.gov/db/nation/nis/NIS_2007_INTRODUCTION.pdf (Accessed May 6,
2010).
U.S. Census Bureau (2007). Cumulative Estimates of Population Change for the United States,
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HCUP (9/3/2010)
41
Del #45.1: NIS Comparison Report, 2007
Coronary Artery Disease 81
의사와 병원의 관상동맥 중재술 경험이 많을수록
환자의 예후가 좋다
조 상 호 교수 한림대학교 성심병원 순환기내과
Summary
배경
관상동맥 중재술(percutaneous coronary intervention, PCI)을
(45–100; 0.87%, 6.40%), 2번째 군(16–44; 1.15%, 7.75%)]이
얼마나 많이 시술하는 병원인지 혹은 얼마나 많이 시술하는 의
가장 적은 1번째 군(≤15; 1.68%, 10.91%)보다 의미 있게 적었다
사인지에 따른 환자의 예후에 대한 연구는 없었다.
(P <0.001). Spline 분석에 의해서도 병원과 의사의 시술 총량이
환자의 예후와 연관성이 있었다. 마찬가지로, 시술량이 많은 경
방법 및 결과
우 입원 기간과 의료 비용이 의미 있게 적었다(P <0.001).
2005-2009년까지 Healthcare Cost and Utilization Project’s
Nationwide Inpatient의 데이터베이스를 근간으로 하여 단
결론
면적 연구를 시행하였다. 환자들은 ICD 9(International
전반적으로, PCI 후의 사망은 적었다. 의사와 병원의 PCI 시술이
Classification of Diseases)과 Clinical Modification
증가할수록 환자의 심혈관 사건 발생, 입원 기간 및 입원 비용이
procedure code(36.06, 36.07)로 찾아내었다. 의사와 병원의 시
감소하였다.
술 총량은 특별한 선별 기법으로 찾아내었고, 그 총량에 따라 4
개 군으로 분류하였다. 3개의 순차적 수준에 따른 다면적 복합 모
델을 만들어서 활용하였다. 일차 목표 변수는 입원 중 사망이고,
이차 목표 변수는 입원 중 사망과 시술 전후의 합병증 발생이다. 연
구 기간 동안 미국에서 시행된 총 2,243,209건의 PCI 중 457,498건
이 분석되었다. 입원 중 사망은 1.08%였고 전체 합병증 발생률
은 7.10%였다. 일차와 이차 목표 변수는 시술 총량이 가장 많은
4-2번째 군[annual procedural volume; primary and
secondary outcomes, 4번째 군(>100; 0.59%, 5.51%), 3번째 군