General Surgery 2009
Surgical Site Infection Surveillance (SSIS) for
General Surgery
Wexford General Hospital Surgical Site Infection
(SSI) data report
2009 Annual report
Amended 06/11/12
General Surgery 2009
Index
Page
Key points
3
Foreword
4
Methodology
4
Steering committee
5
Results
6
Section 1: General Demographics
Age
6
Gender
7
Procedure
8
Endoscopy
9
Grade of surgeon
9
Wound classification
10
Anaesthesia
11
ASA classification
11
Section 2: Microbiology
SSI organisms
13
Antimicrobial resistance/susceptibility
14
Section 3: Timelines
Length of stay
14
Length of stay pre-procedure
14
Length of stay to development of SSI
14
Section 4: Risk
NNIS Risk index
15
Appendices
Appendix I
BMI
17
Appendix II
Multiple procedures
17
Appendix III Duration of procedure
18
2
General Surgery 2009
Key Points
•
In 2009, 28 surgical site infections (SSIs) were recorded out of 641 patients. The
crude SSI rate was 4.4%.
•
More men had procedures (n= 327) than women (n= 314). SSI rates were 4.3%
and 4.4% respectively
•
Age ranged from 1 year to 95 years. The SSI rate was highest in those in the 6675 year age group (6.9%) and the 56-65 year age group (7.1%).
•
The most common procedures performed were; Other Integumentary (n=171),
Appendicectomy (n=132) and Cholecystectomy (n=103). The highest SSI rates
occurred in Laparotomies at 26% (5 SSIs in 19 procedures), and small bowel
surgeries at 23.5% (4 SSIs in 17 procedures)
•
SSI rates were higher in emergency procedures, in open procedures and in those
who had general anaesthesia.
•
SSI rate was 4.9% in wounds classified as clean/contaminated, rising to 9.6% in
dirty/infected classified wounds. There were no SSIs were recorded for clean
wounds.
•
The SSI rate was similar (4.6%, 4.3%) in patients classed as either healthy
(ASA1) or mild systemic (ASA 2). The SSI rate decreased (2%) in patients with
severe systemic disease (ASA 3). No SSIs were recorded in patients classed with
incapacitating systemic disease (ASA 4), and no patients were recorded as being
moribund (ASA 5).
•
A risk score was assigned to each patient based on the individual’s ASA category,
length of surgery and wound classification. The overall Risk Index, which is a
sum of the three risk scores, was calculable on 588 patients. Of these 66% scored
a risk index of 0. The SSI rate was 2.8% (RI 0), 8.1% (RI 1) and 2.8% (RI 2) as
the risk index increased.
•
A variety of enteric and commensal microorganisms were identified.
3
General Surgery 2009
Foreword
Healthcare Associated Infection (HCAI) is recognised more and more by patients and
public alike as an issue with the capacity to touch everyone’s life. There is an increasing
demand for consistent valid data regarding HCAIs not only from the Government and the
Public but also from the Healthcare Professions. It is only by monitoring and trying to
understand why HCAIs occur that we can put in place measures to reduce the occurrence
of such untoward events.
The data provides important information to underpin infection prevention and control
action plans at local and national levels by:
• Providing risk adjusted measures of performance over time and highlighting
potential areas of concern whilst stressing areas of good practice;
• Improving understanding in relation to practice. The ability to compare results
with a broad range of service providers both within the UK, Europe and USA will
be particularly important in this regard;
• Assist in monitoring the impact of any interventions introduced in surgical
practice.
Surveillance Methodology
The surveillance methodology is based on the National Nosocomial Infection
Surveillance (NNIS) System developed by Centres for Disease Control and Prevention
(CDC), Atlanta, Georgia, USA.
Primary data collection related to the first thirty days post-surgery. If an implantable
device was involved this was extended for at least one year post surgery. Formal post
discharge surveillance was not performed: patients were asked to attend at dressing clinic
or accident & emergency if a surgical site infection (SSI) was suspected.
Surgical site infection surveillance (SSIS) data were analysed on seventeen types of
procedure.
Full exclusions from analysis include any patients where:
• SSI status was not recorded
• Procedure was not recorded
In any table, the number of patients with missing/non recorded data is included as a
footnote. This indicates non-compliance with data recording. Therefore, in reading the
tables the total numbers may not add up to the total number of procedures performed on
patients in the whole study.
We would like to thank all the healthcare professionals who participated in all aspects of
the surveillance. It would have been impossible to produce this report without their
support.
4
General Surgery 2009
Steering Committee Members
Ms Lily Byrne
General Manager (Chair)
Mr Seamus Butler
Director of Information systems
Dr Brian Carey
Consultant Microbiologist
Ms Margaret Curran
Quality and risk manager
Mr Bernard Finnegan
Director of Nursing
Dr Francois Gardeil
Obstetrician
Dr Ashling Hogan
Specialist Surgical Registrar
Ms Deirdre Lambert
Pharmacist
Dr Orla McCormack
Specialist Surgical Registrar
Mr Ken Mealy
Consultant surgeon
Dr Ann Marie O’Byrne
Consultant in Public Health Medicine
Dr Colette O’Hare
Surveillance Scientist, Public Health
Ms Rose O’Leary
Theatre CNM2
Ms Eithne O’Sullivan
SSIS Surveillance Manager
Ms Rebecca Pierce
Surgical Nurse Manager
Mr Nicky Power
ICT Systems analyst
Ms Niamh Purcell
Surveillance Scientist, Microbiology Laboratory
Ms Emer Ward
Nurse Specialist Infection and Prevention & Control
5
General Surgery 2009
Results
This report refers to 641 patients admitted between 1 Jan and 31 Dec 2009 for designated
procedures.
Data was collected on seventeen procedures. Each patient had one main procedure
recorded. Fifteen patients had more than one procedure performed through the same
incision (second procedure is not recorded in this study). Two of these patients
developed an SSI.
Twenty-eight surgical site infections were diagnosed. There were 21 superficial incisional
type SSIs, 2 deep incisional SSIs and 4 organ SSIs.
SSI rate is a percentage and is calculated as the number of SSIs divided by the total
number of patients. The crude SSI rate was 4.4%.
. Since the beginning of the SSIS process for general surgery in Wexford General
Hospital, crude Surgical Site Infection rates have been steadily decreasing. In 2007
the rate was 9%, in 2008 it was 5.4% and in 2009 it was 4.4%.
Section 1: General demographics
Age
The age range was 1 year to 95 years old, with a median age of 48 years. The highest SSI
rate occurred in the age groups 15-35 and 56-65 (Figure 1, Table 1).
300
12
250
10
200
8
150
6
100
4
50
2
0
SSI rate %
Number of procedures
Figure 1: 2009 Age grouping and SSI rates
0
0-2
3-14
15-35 36-45 46-55 56-65 66-75
76+
Age band
Number of procedures
SSI rate
* The 0-2 age group was included for consistency with the Northern Ireland SSIS report.
6
General Surgery 2009
Table 1: SSI rate and age group 2009
No. of
Age Group
procedures No. of SSI SSI rate %
0-2
6
0
0
3-14
77
0
0
15-35
151
10
6.6
36-45
77
1
1.3
46-55
91
2
2.2
56-65
98
7
7.1
66-75
87
6
6.9
76 +
54
2
3.7
Total
641
28
Gender
Procedures were carried out on 327 men and 314 women (Figure 2).
Figure 2: Procedures by gender
Procedures by gender
female
49%
male
51%
SSI rates between men and women were very similar. Men had an SSI rate of 4.3% and
women, 4.4%.
Figure 3: Gender and SSI
SSI rate and gender
female, 4.4
male, 4.3
7
General Surgery 2009
Procedure
The most common procedures performed were; Other Integumentary (n=171),
appendicectomy (n=132) and cholecystectomy (n=132). Laparotomies had the highest
SSI rate at 26.3% (Table 2).
Table 2: Procedures by gender and SSI
Total no.
Total
SSI
of
No.
rate %
Procedure*
procedures SSI
Appendicectomy
132
7
5.3
Cholecystectomy
103
Gastric surgery
4
Herniorrhaphy
82
Varicose vein
15
Colon surgery
52
10
19.2
Small bowel surgery
17
4
23.5
Mastectomy
2
Laparotomy
19
5
26.3
Limb amputation
11
Thoracic surgery
1
Other integumentary system
171
2
1.1
Other prosthesis
1
Soft tissue trauma
7
Skin graft
4
Other digestive system
7
Other breast surgery
13
Total
641
28
In 2009 data was collected on twenty types of operative procedures. There were no bile duct/pancreatic surgeries, splenectomy
surgeries or endocrine system surgeries.
8
General Surgery 2009
Procedure status
The SSI rate for emergency procedures (6.4%) was higher than the SSI rate for elective
procedures (2.8 %) (Figure 4).
Figure 4: Procedure status and SSI
Procedure status and SSI
Number of procedures
400
350
10
300
18
250
200
150
350
263
100
50
0
Elective
Emergency
Procedure status
Procedure w ithout SSI
Procedure w ith SSI
Endoscopic approach
The rate of SSI for patients who had an endoscopic procedure was 2.2% as compared to a
rate of 5% for those who had an open procedure (Table 3).
Table 3: Endoscopic approach
Endoscope
No. of patients
Yes
138
No
474
% patients
22.5
77.5
No. SSIs
3
24
SSI rate %
2.2
5.0
Non recorded data=29 (of which one was an SSI)
Grade of operating surgeon
All patients admitted for a procedure are admitted under a consultant surgeon. The
surgical procedure may be performed directly by the surgeon or by one of his team under
his supervision as outlined in table 4.
Table 4: Grade of operating surgeon
Primary Operator
No. of
procedures
Consultant surgeon
315
Registrar
216
Special registrar
33
Senior house officer
68
% of
procedures
50.0
34.2
5.2
10.8
No. of SSI
18
8
1
0
SSI rate %
5.7
3.7
3.0
Non recorded data=9 (of which one was an SSI)
9
General Surgery 2009
Consultant surgeons performed 50% of procedures and had an SSI rate of 5.7%.
Consultant surgeons generally perform procedures on patients with a higher NNIS risk
index than those of other grades.
The NNIS risk index of patients shown by the grade of surgeon who performed the
procedure is highlighted in Table 10 p17.
For 317 procedures where the consultant was not the primary operator, 146 (46%)
recorded that the consultant had assisted. ‘Did the consultant assist’- question was not
answered in 18 (5.7%) cases.
Surgical procedure and wound classification
Classification of a wound impacts on the SSI rate. This is seen in Table 5 and figure 5,
where the SSI rate in clean wounds is 0% compared with a rate of 9.6% in dirty/infected
wounds.
Table 5: Surgical procedures by wound classification
Procedure
Appendicectomy
Cholecystectomy
Gastric surgery
Herniorrhaphy
Varicose vein
Colon surgery
Small bowel surgery
Mastectomy
Laparotomy
Limb amputation
Thoracic surgery
Other integumentary
system
Other prosthesis
Soft tissue trauma
Skin graft
Other digestive system
Other breast surgery
Total
No. of SSIs by wound class
SSI rate (%) by wound
class
*
Wound Classification
Clean
0
0
0
75
15
0
0
2
0
2
0
Clean/
contaminated
82
94
3
3
0
26
7
0
11
3
1
Contaminated
32
7
1
3
0
15
7
0
4
0
0
Dirty/infected
17
2
0
0
0
10
3
0
4
5
0
97
1
1
3
2
13
211
0
31
0
4
1
1
0
267
13
12
0
1
0
2
0
84
8
30
0
1
0
1
0
73
7
0
4.9
9.5
9.6
Total
No
131
103
4
81
15
51
17
2
19
10
1
170
1
7
4
6
13
635
28
Non recorded data=6
10
General Surgery 2009
Figure 5: SSI rate by wound class
300
12
250
10
200
8
150
6
100
4
50
2
0
0
Clean
Clean/contaminated Contaminated
SSI rate (%)
Number of
procedures
SSI rate by wound class
Dirty/infected
Wound class
No of procedures
SSI rate
Anaesthesia
Table 6: Type of anaesthesia
Most patients (84%) had a general anaesthetic.
Anaesthesia
Local
Regional
General
No. of patients
37
58
532
% patients
5.9
9.2
84.5
No. SSIs
0
2
26
SSI rate %
0
3.4
4.9
Non recorded data=14
ASA classification
The American Society of Anaesthesiology (ASA) classification scores patients on a five
point scale from healthy to moribund. Seventy one percent of patients were classified as
healthy.
In 2009, the SSI rate was similar (4.6% vs 4.3%) for both healthy patients and those with
mild systemic disease (ASA 1 and 2). The SSI rate was 2% in patients classified with
severe systemic disease (ASA 3). No SSIs were detected in patients with incapacitating
systemic disease (ASA 4). No patients were classed as ASA 5 (Table 7).
11
General Surgery 2009
Table 7: Surgical procedures by ASA classification
Procedure
Appendicectomy
Cholecystectomy
Gastric surgery
Herniorrhaphy
Varicose vein
Colon surgery
Small bowel
surgery
Mastectomy
Laparotomy
Limb amputation
Thoracic surgery
Other
integumentary
system
Other prosthesis
Soft tissue trauma
Skin graft
Other digestive
system
Other breast
surgery
Total
No. of SSIs by
ASA category
SSI rate (%) by
ASA category
ASA classification
Healthy
1
117
74
4
45
13
30
Mild
systemic
disease
2
10
21
0
28
2
14
Severe
systemic
disease
3
2
7
0
7
0
5
Incapacitating
systemic
disease
Moribund Total
4
5
0
0
129
0
0
102
0
0
4
0
0
80
0
0
15
3
0
52
17
1
0
0
0
2
1
0
17
1
0
11
0
0
1
165
8
1
7
1
0
4
1
6
3
1
4
0
3
6
0
128
0
6
3
23
1
1
0
14
0
0
0
0
0
0
0
0
0
0
0
5
1
0
1
0
10
452
0
116
2
50
0
7
0
0
21
5
1
0
0
4.6
4.3
2.0
0
0
1
7
3
7
12
625
27
Non recorded data= 16 , (of which one was an SSI)
In 2009 the SSI rate is highest in healthy patients (ASA 1), and decreases in those with
mild systemic disease (ASA 2) and again in those with severe systemic disease (ASA 3)
(Figure 6). In contrast, the data from 2008 showed that the SSI rate increased with ASA
class.
12
General Surgery 2009
500
450
400
350
300
250
200
150
100
50
0
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
ASA 1
ASA 2
ASA 3
ASA 4
SSI rate (%)
Number of procedures
Figure 6: SSI rate by ASA classification
ASA 5
ASA class
Number of procedures
SSI rate
Section 2: Microbiology
For 2009, 28 SSIs were identified
• In 5 cases the SSI was diagnosed without microbiological testing
• In 2 cases swabs were sent to the laboratory but no organism was isolated.
Table 8 lists the organisms identified in the other 21 SSIs. (Refer to Table 2 for the
number of SSIs per procedure). Note more than one organism can be isolated from any
one SSI.
Table 8: SSI organisms identified from procedures.
Procedure
SSI organisms reported
Appendicectomy
Colon surgery
Small bowel
Laparotomy
Escherichia coli
Klebsiella pneumoniae
Coagulase negative staphylococci
Anaerobes
Enterococcus spp
Escherichia coli
Anaerobes
Enterobacter spp
Coagulase negative staphlococci
Enterococcus spp
Klebsiella spp
Candida spp
Other strep spp
Escherichia coli
Anaerobes
Enterobacter spp
Acinetobacter spp
Candida spp
Anaerobes
Enterococcus spp
Coagulase negative staphlococci
Escherichia coli
Psuedomonas spp
Stenotrophomonas spp
13
General Surgery 2009
Antimicrobial resistance/susceptibilities of SSI organisms
•
One MSSA and zero MRSAs
•
For gram negative organisms that had antibiotic resistance recorded (other than
pseudomonas spp):
46.6% were resistant to augmentin
20.0% were resistant to gentamycin
20.0% were resistant to ciprofloxacin
13.3% were resistant to tazocin
•
Pseudomonas spp – both isolates sensitive to ciprofloxacin, gentamycin,
meropenem, tazocin
One Stenotrophomonas spp sensitive to ciprofloxacin, gentamicin and tazocin,
resistant to meropenem
•
Section 3: Timelines
This section shows duration of procedures, the time it takes to develop an SSI, and length
of stay in hospital. 0 days indicates a day patient.
Length of stay
Length of stay (LOS) in hospital ranged between 0-98 days, with a median stay of 2 days.
For the common procedures, median LOS was 1 day for cholecystectomy (range 0-29).
For appendicectomy, the median LOS was 3 days (range 1-15). Median LOS for other
integumentary procedures was 1 days (range 0-37).
Length of stay pre-procedure
The average length of stay between admission and procedure was one day. The longest
length of stay pre-op was 51 days
Length of stay to development of SSI
82 % of all SSIs developed within two weeks following the procedure (figure 7). Nine
SSIs (32%) were detected following discharge, 7 of them by re-admission. (NB
formalised post discharge surveillance was not in place in 2009).
14
General Surgery 2009
Figure 7: Length of time to develop SSI
Number of SSI cases
Time (days) from Procedure to SSI
10
9
8
7
6
5
4
3
2
1
0
1
3
5
7
9
11 13 15 17 19 21 23 25 27 29
Days
Number of SSI
Section 4: Risk
Incidence of SSI by risk index and category of surgical procedure
There are a number of factors that may influence the risk of infection. Data has been
stratified using the US National Nosocomial Infections Surveillance (NNIS) system risk
index (RI).
This combines three major risk factors. Each of the major risk factor components is
individually scored as either 0 or 1 for each patient.
These risk factors are:
• The ASA pre-operative assessment score (score 1 if ASA is 3, 4 or 5)
• Wound classification (score 1 if contaminated or dirty/infected)
• Duration of procedure (score 1 if duration exceeds specified T value)
NNIS risk index cannot be calculated if any of the individual risk factor components are
missing. Because there are no T values assigned to both ‘Soft tissue trauma’ and ‘Other
breast surgery’, the NNIS risk index cannot be calculated for these procedures. Therefore
all patients who had these procedures and any other patients where one of the major risk
factors was not recorded are omitted from the following risk analysis (which refers to 53
procedures).
For each patient the sum of each score of the three risk components is calculated. This is
the NNIS system risk index (RI). Table 9 and Figure 8 shows the NNIS risk index for all
procedures
15
General Surgery 2009
Table 9: NNIS risk index for all procedures
SSI
No of patients NNIS risk index
RI 0
RI 1
RI 2
Yes
11
13
1
No
380
148
35
Total
391
161
36
SSI rate
2.8
8.1
2.8
RI 3
0
0
0
0
*Data on at least 30 procedures in a given risk index category must be available in order to present results for that category.
Figure 8: All procedures and SSI rates stratified by risk index
9
8.1
8
SSI rate (%)
7
6
5
4
3
2.8
2.8
2
1
0
RI 0 (n=391)
RI 1 (n=161)
RI 2 (n=36)*
RI 3 (n=0) *
Ris k Inde x (num be r of proce dur e s )
*Data on at least 30 procedures in a given risk index category must be available in order to present results for that category.
As the NNIS risk index increased, consultant surgeons performed an increasing
percentage of procedures (table 10). This number rose from 47% of patients with risk
index 0 to 63% of those with risk index 3. The grade of surgeon performing the
procedure by SSI is shown in table 4 on page 9.
Table 10: NNIS risk index for all procedures by grade of surgeon
SSI
No of patients NNIS risk index
RI 0
RI 1
RI 2
RI 3
Consultant
181
87
24
0
Registrar
139
48
6
0
Special registrar
22
7
1
0
SHO
46
15
5
0
Total
388
157
36
0
16
General Surgery 2009
APPENDICES
Appendix I
BMI
The SSIS form included a question on patient weight and height in order to calculate the
body mass index. No inferences on SSIs should be made from this data as it was only
recorded on 22 cases.
BMI
Underweight
Normal
Overweight
Obese
(<17.9)
(18-24.9)
(25-29.9)
(>30)
No of
patients
0
1
7
14
No SSIs
0
0
0
0
Appendix II
Multiple procedures
There were 13 patients with more than one procedure performed through the same
incision during the same operation. Of these, 3 had a longer duration of surgery than the
procedural T value. The primary procedures involved are shown below. The second
procedure is not recorded in this surveillance program.
No of patients with more than one
procedure performed through the same
Primary procedure
incision during the same operation
Appendicectomy
2
Cholecystectomy
Gastric surgery
Herniorrhaphy
2
Varicose vein
Colon surgery
4
Small bowel surgery
1
Mastectomy
1
Laparotomy
1
Limb amputation
Thoracic surgery
2
Other integumentary system
Other prosthesis
Soft tissue trauma
NA*
Skin graft
Other digestive system
Other breast surgery
NA*
*NA- Procedural T values have not been assigned for these procedures
17
General Surgery 2009
Appendix III
Duration of procedures
The distribution of duration of operation for different procedures was determined by the
NNIS and the 75th percentile was identified and used as a cut point (T). This has resulted
in a T (time) value being assigned to different procedure classes. In 2009 there were 33
procedures which exceeded their T value
Time of procedures
Procedure
Appendicectomy
Cholecystectomy
Gastric surgery
Herniorrhaphy
Varicose vein
Colon surgery
Small bowel surgery
Mastectomy
Laparotomy
Limb amputation
Thoracic surgery
Other integumentary
system
Other prosthesis
Soft tissue trauma
Skin graft
Endocrine system
Other digestive
system
Splenectomy
Other breast surgery
T value
(mins)
60
120
180
120
120
180
180
120
120
60
180
120
120
NA*
120
180
180
120
NA*
Total number of patients whose
procedure exceeded T value
16
3
3
1
4
2
2
2
NA*
NA*
*NA- Procedural T values have not been assigned for these procedures
18