Original Research—Head and Neck Surgery
Oropharyngeal Contamination
Predisposes to Complications after Neck
Dissection: An Analysis of 9462 Patients
Otolaryngology–
Head and Neck Surgery
2015, Vol. 153(1) 71–78
Ó American Academy of
Otolaryngology—Head and Neck
Surgery Foundation 2015
Reprints and permission:
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DOI: 10.1177/0194599815581808
http://otojournal.org
Umang Jain1, Jessica Somerville, MD2, Sujata Saha1,
Nicholas James Hackett1, Jon P. Ver Halen, MD3,
Anuja K. Antony, MD, MPH4, and Sandeep Samant, MD2
No sponsorships or competing interests have been disclosed for this article.
Abstract
Objective. While neck dissection is important in the treatment of head and neck cancer, there is a paucity of studies
evaluating outcomes. We sought to compare preoperative
variables and outcomes between clean and contaminated
neck dissections, using the 2006-2011 American College of
Surgeons National Surgical Quality Improvement Program
(ACS NSQIP) data sets.
Study Design. Retrospective review of prospectively maintained database.
Setting. Multicenter (university hospitals; tertiary referral
centers).
Subjects and Methods. A retrospective review was performed of the NSQIP database to identify patients
undergoing neck dissection in clean vs oropharyngeal
contaminated cases. Clinical factors, comorbidities, epidemiologic factors, and procedural characteristics were
analyzed to identify factors associated with 30-day postoperative adverse events, including medical and surgical
complications, unplanned reoperation, and mortality.
Bivariate and multivariable analyses were performed for
the outcome of one or more adverse events.
Results. In total, 8890 patients had clean neck dissections,
while 572 patients had neck wound contamination with oropharyngeal flora. On multivariable regression analysis, oropharyngeal contamination was a significant risk factor for
surgical complications (odds ratio [OR], 3.42; 95% confidence interval [CI], 1.96-5.96; P \ .001). However, medical
complications and mortality were not significantly different
between the 2 cohorts. This finding persisted after subgroup
analysis, with removal of all thyroidectomy patients from
analysis (OR, 2.33; 95% CI, 1.25-4.36; P = .008).
Conclusion. Using the ACS-NSQIP data set, this study found
an increased risk of surgical complications in the setting of
contaminated neck dissections. These data should be used
for patient risk stratification, informed consent, and to guide
further research.
Keywords
neck dissection, clean cases, contaminated cases, NSQIP,
outcomes, mortality
Received September 17, 2014; revised March 11, 2015; accepted
March 24, 2015.
S
urgical neck dissection is used as a diagnostic, staging,
and therapeutic modality and is thus an essential tool
for the head and neck oncologic surgeon. To date,
studies evaluating neck dissection have only been in conjunction with other procedures, are limited to single-surgeon or
single-institution experiences, lack current review, and do not
use large database analyses.1-5 The American College of
Surgeons National Surgical Quality Improvement Program
(ACS NSQIP) is the premier tool for population-based analyses of critical health care issues, including registry-based
trials, risk adjustment, surgical outcomes, and cost.6,7
The current study revisits the topic of wound contamination by oral and pharyngeal secretions (referred to as oropharyngeal contamination in this article) after neck
dissection. Prior single-institution studies have demonstrated
a significant increase in postoperative wound infection in
neck dissections with concomitant entry into the oropharyngeal and/or respiratory tracts.8-10 While it is generally
accepted that concomitant resections on the oropharyngeal
1
Northwestern University, Feinberg School of Medicine, Chicago, Illinois,
USA
2
Department of Otolaryngology–Head and Neck Surgery, University of
Tennessee Health Science Center, Memphis, Tennessee, USA
3
Department of Plastic, Reconstructive, and Hand Surgery, Baptist Cancer
Center–Vanderbilt Ingram Cancer Center, Memphis, Tennessee, USA
4
Division of Plastic and Reconstructive Surgery, University of Illinois at
Chicago, Chicago, Illinois, USA
This article was presented at the 2014 AAO-HNSF Annual Meeting & OTO
EXPO; September 21-24, 2014; Orlando, Florida.
Corresponding Author:
Jon P. Ver Halen, MD, Department of Plastic, Reconstructive, and Hand
Surgery, Baptist Cancer Center, 3268 Duke Circle, Germantown, TN
38139, USA.
Email: [email protected]
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72
Otolaryngology–Head and Neck Surgery 153(1)
tract have the added risk of increasing surgical infections,
verification of this risk on a large scale across institutions, its
impact on global postsurgical outcomes, and the influence of
further contributing factors have not been performed.
unplanned readmission (only available for procedures in
2011), or mortality. The cohort of patients experiencing
complications consisted of any patient who had 1 or more
adverse event within 30 days of the procedure.
Materials and Methods
Adjusted Risk Factors
All study aspects were reviewed and approved by the institutional review boards of all authors’ institutions (Northwestern
University, University of Tennessee–Memphis, Baptist Cancer
Center, and University of Illinois–Chicago). A retrospective
analysis was performed on data collected from the 2006-2011
NSQIP participant use files. The data collection methods for
NSQIP have been previously described.11-13 Briefly, 240 variables, including patient demographics, comorbidities, perioperative details, and 30-day risk-adjusted postoperative outcomes,
are prospectively collected for each patient at participating institutions within the United States. To ensure accuracy, certified
nurse reviewers are rigorously trained to collect patient information according to standardized definitions, with the data undergoing regular audit. The eligible study population included all
patients undergoing inpatient and outpatient surgery at any of
the over 400 NSQIP participant hospitals, which included
approximately 2 million patients as of December 31, 2012. This
included a cross section of all patients undergoing neck dissection in North America, including rural and urban hospitals, and
teaching and nonteaching hospitals.
For this study, NSQIP was first queried to identify all neck
dissection procedures with Current Procedural Terminology
(CPT) codes in head and neck extirpation procedures, without
involvement of the oropharyngeal tract (ie, ‘‘clean’’ cases).
This included primary, other, or concomitant codes, including
60252 (thyroidectomy with limited central neck dissection),
60254 (thyroidectomy with lymph node dissection [LND]),
38700 (suprahyoid LND), 38724 (modified radical neck dissection [MRND]), 38720 (radical neck dissection [RND]),
42426 (parotidectomy with lymph node dissection), and 69155
(mastoid resection with lymph node dissection). Second,
NSQIP was queried to identify all neck dissection procedures
with CPT codes in extirpative procedures with involvement of
the oropharyngeal tract (ie, ‘‘contaminated’’ cases). This
included primary, other, or concomitant codes, including
41153 (partial glossectomy with floor of mouth resection and
LND), 31390 (pharyngolaryngectomy and LND), 31395 (pharyngolaryngectomy and LND with reconstruction), 41135 (glossectomy and LND), 41145 (glossectomy and LND), and
41155 (composite mandible resection and LND). Any patients
with CPT codes that caused overlap between ‘‘clean’’ and
‘‘contaminated’’ were considered ‘‘contaminated’’ cases during
cohort analysis. Patients with incomplete demographic data
(ie, no sex information) were excluded. A total of 9462
patients were thus identified.
Patient demographics, medical comorbidities, and procedural characteristics were analyzed as potential risk factors.
Obesity was defined as body mass index (BMI) greater than
or equal to 30 kg/m2. Procedural characteristics included
were operative time and anesthesia duration. We included
anesthesia time in regression analyses to control for underlying differences in the ‘‘clean’’ and ‘‘contaminated’’
cohorts (discussed in detail below).
Outcome of Interest
The primary outcome of interest for the study was 1 or
more adverse events in the 30 days following neck dissection. We defined an adverse event as any of the following:
surgical complications, medical complications, reoperation,
Statistical Analysis
Univariate analysis and multivariable logistic regression models
were used to determine significant predictors of complications
in patients. Individual variables with 10 event occurrences
showing association with complications at a significance level
of P .20 in the univariate analysis were included in multivariable models. Based on these criteria, the following variables
met criteria for inclusion in multivariable logistic regression
analysis: tobacco use; alcohol use; chronic steroid/immunosuppression use; preoperative radiotherapy less than 90 days from
the index procedure; chemotherapy less than 30 days from the
index procedure, previous operation less than 30 days from
the index procedure, dyspnea, hypertension requiring medication, chronic obstructive pulmonary disease (COPD), previous percutaneous intervention (PCI), transient ischemic
attack (TIA), previous stroke or CVA, hemiplegia, disseminated cancer, open or infected wound, American Society
of Anesthesiologists (ASA) levels 3 to 5, obesity, operative
time, anesthesia duration, and age. Notably, thyroidectomy
with neck dissection was more commonly performed than
other neck dissection procedures (5277 of all cases, or
56% of the total). This inherent bias of the NSQIP data set
resulted in a relative overrepresentation of ‘‘clean’’ thyroidectomy procedures, although approximately 25% of
‘‘contaminated’’ cases also included thyroidectomies.
Consequently, we performed a subgroup multivariable
analysis of the effect of contaminated neck status as a predictor of adverse events, with the removal of all thyroidectomy procedures (both ‘‘clean’’ and ‘‘contaminated’’).
This left 4183 patients for evaluation. Based on power calculations, all analyses were sufficiently powered to detect
significant differences with a probability of at least .05. A
Hosmer-Lemeshow (HL) test and C-statistic for calibration
were computed to assess the goodness-of-fit model. We
chose the HL test and C-statistic to assess goodness of fit,
since in a large dataset (such as NSQIP), it would yield the
most sensitivity with respect to significant differences
between our observed and model-predicted values.
Results
A total of 9632 patients were extracted from the 2006-2011
NSQIP data sets. In total, 172 patients had incomplete data,
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Jain et al
73
Table 1. Patient Case Totals vs Current Procedural Terminology (CPT) Code Type and Description.
CPT Code and Description
No. of Cases
31390 Pharyngolaryngectomy, with radical neck dissection; without reconstruction
31395 Pharyngolaryngectomy, with radical neck dissection; with reconstruction
38700 Suprahyoid lymphadenectomy
38720 Cervical lymphadenectomy (complete)
38724 Cervical lymphadenectomy (modified radical neck dissection)
41135 Glossectomy; partial, with unilateral radical neck dissection
41145 Glossectomy; complete or total, with or without tracheostomy, with unilateral radical neck dissection
41153 Glossectomy; composite procedure with resection floor of mouth, with suprahyoid neck dissection
41155 Glossectomy; composite procedure with resection floor of mouth, mandibular resection, and radical neck
dissection (Commando type)
42426 Excision of parotid tumor or parotid gland; total, with unilateral radical neck dissection
60252 Thyroidectomy, total or subtotal for malignancy; with limited neck dissection
60254 Thyroidectomy, total or subtotal for malignancy; with radical neck dissection
69511 Mastoidectomy; radical
thus leaving 9462 patients for analysis. Of these 9462
patients who underwent primary or adjunctive neck dissection, 8890 were considered ‘‘clean’’ neck dissections, and
572 were considered ‘‘contaminated’’ neck dissections. A
total of 128 (1.44%) ‘‘clean’’ patients and 19 (3.32%)
‘‘contaminated’’ patients had a history of radiation therapy
(by NSQIP definition). A breakdown of case totals by CPT
procedure code is found in Table 1. With regard to postoperative entries for diagnosis codes, there were 3154 thyroid primary cases, 536 lymph node primary cases, 280
oropharyngeal primary cases, 183 skin primary cases, 133
larynx primary cases, and 90 parathyroid primary cases. Of
the cases, 477 had diagnosis codes not directly attributable
to a specific head and neck cancer subset, while 4609 did
not have any diagnosis code recorded. In total, 990 patients
(10.5%) had at least 1 adverse event within 30 days of the
primary procedure. The 2 patient cohorts were significantly different with respect to a number of preoperative
and operative characteristics on univariate analysis (Table
2), indicating a higher level of attendant comorbid disease
and degree of procedural complexity in the ‘‘contaminated’’ cohort.
On univariate analysis, nearly every category of complication was significantly increased in the ‘‘contaminated’’
compared with the ‘‘clean’’ cohort. This included any complication (P \ .001), any surgical complication (P \ .001),
any medical complication (P \ .001), unplanned reoperation (P \ .001), and mortality (P \ .001) (Table 3). The
most common surgical complication was superficial surgical
site infection (SSI), with a total of 131 cases. Of these 131
infections, 94 (1.06%) were in clean cases, and 37 (6.47%)
were in contaminated cases (P \ .001). The most common
medical complication was blood transfusion (P \ .001),
given intraoperatively or within 72 hours of surgery, followed by pneumonia (P \ .001) and ventilator dependence
greater than 48 hours postoperatively (P \ .001).
117
81
120
425
2675
184
41
36
113
392
4569
708
1
We subsequently performed risk-adjusted multivariable logistic regression to analyze factors associated with surgical or medical complications, while controlling for the extensive baseline
differences between cohorts. The incidence of any surgical complication was most strongly associated with ‘‘contaminated’’
cases (odds ratio [OR], 3.42; 95% confidence interval [CI],
1.96-5.96; P \ .001) (Table 4). Other factors included a history
of radiation therapy within 90 days of the index procedure (P =
.027) and increasing anesthesia duration (P = .006; HosmerLemeshow [HL] test = 0.370). Medical complications were not
significantly associated with ‘‘contaminated’’ case type (P =
.810). However, they were significantly associated with chronic
steroid/immunosuppression use (P = .006), chemotherapy within
30 days prior to the index procedure (P = .004), dyspnea (P =
.017), COPD (P = .026), ASA classes 3 to 5 (P \ .001),
increasing anesthesia duration (P \ .001), and increasing age
(P \ .001; HL test = 0.049) (Table 5).
Notably, thyroidectomy with neck dissection was more
commonly performed than other neck dissection procedures
(5277 of all cases, or 56% of the total). This inherent bias of
the NSQIP data set resulted in a relative overrepresentation of
‘‘clean’’ thyroidectomy procedures, although approximately
25% of ‘‘contaminated’’ cases also included thyroidectomies.
Consequently, we repeated our multivariable analysis of the
effect of contaminated neck status as a predictor of adverse
events, with the complete removal of all thyroidectomy procedures (both ‘‘clean’’ and ‘‘contaminated’’). This resulted in a
subgroup population of 4183 patients. Analysis of this subgroup demonstrated the same result: contaminated neck dissection is associated with statistically significant increased risk of
surgical complications, as well as reoperation (OR, 2.33 and
1.87; P = .008 and 0.006, respectively) (Table 6).
Discussion
Despite being a mainstay procedure in head and neck surgery, neck dissection has limited data regarding factors
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74
Otolaryngology–Head and Neck Surgery 153(1)
Table 2. Patient Demographics vs Neck Dissection Cohort (Univariate Analysis).a
Characteristic
Clinical characteristics
Smokers
Alcohol use
Steroid use
Preoperative radiotherapy
Chemotherapy
Previous operation \30 days
Comorbidities
Diabetes
Dyspnea
Hypertension
COPD
Congestive heart failure
Bleeding disorders
Previous PCI
Previous cardiac surgery
Stroke (with neurological deficit)
TIA
Hemiplegia
Disseminated cancer
ASA Levels 3-5
Obesity
Procedure characteristics, mean 6 SD
Operative time, min
Duration of anesthesia, min
Age, y
Clean (n = 8890)
Contaminated (n = 572)
P Value
1327 (14.93)
232 (2.61)
186 (2.09)
128 (1.44)
103 (1.16)
180 (2.02)
236 (41.26)
70 (12.24)
17 (2.97)
19 (3.32)
13 (2.27)
25 (4.37)
.000b
.000b
.159
.000b
.019b
.000b
912 (10.26)
530 (5.96)
3143 (35.35)
213 (2.40)
16 (0.18)
145 (1.63)
240 (2.70)
218 (2.45)
73 (0.82)
111 (1.25)
24 (0.27)
491 (5.52)
3165 (35.60)
3001 (33.76)
66 (11.54)
100 (17.48)
278 (48.60)
70 (12.24)
2 (0.35)
8 (1.40)
32 (5.59)
18 (3.15)
20 (3.50)
14 (2.45)
5 (0.87)
60 (10.49)
441 (77.10)
120 (20.98)
.330
.000b
.000b
.000b
.298
.417
.000b
.302
.000b
.015b
.028b
.000b
.000b
.000b
205.99 6 143.96
267.61 6 155.78
52.28 6 15.92
408.86 6 223.51
486.31 6 240.69
61.45 6 12.7
.000b
.000b
.000b
Abbreviations: ASA, American Society of Anesthesiologists; COPD, chronic obstructive pulmonary disease; PCI, percutaneous intervention; TIA, transient
ischemic attack.
a
Values are presented as number (%) unless otherwise indicated.
b
Denotes significant value, P \.05.
associated with adverse outcomes. Prior single-institution/
single-surgeon studies have cited complication rates after
neck dissection between 3% and 28%.1,5,14 Use of the NSQIP
database offers the ability to systematically track all types of
adverse events (ie, surgical and medical complications, reoperation, readmission, mortality) and their risk factors across
multiple institutions, thus permitting more consistent benchmarking for quality improvement, risk stratification, and
patient informed consent. In the current study, oropharyngeal
contamination was significantly associated with nearly every
type of adverse event on univariate analysis. To account for
numerous significant differences between the ‘‘clean’’ and
‘‘contaminated’’ cohorts (Table 2), multivariable logistic
regression models were used to control for baseline differences. Individual variables with 10 event occurrences
showing association with complications at a significance
level of P .20 in the univariate analysis were included in
multivariable models. Subsequently, on multivariable analysis, ‘‘contaminated’’ status was only associated with surgical
complications, with a compelling OR of 3.42 (P \ .001).
Notably, the NSQIP database has an inherent bias, in that
thyroidectomy with neck dissection was more commonly
performed than other neck dissection procedures. We subsequently performed a subgroup analysis, using all patients
except those with thyroidectomy codes (n = 4183). After
this subgroup analysis, our findings were unchanged (Table
6). Contaminated neck dissection continued to be associated
with a statistically significant increased risk of surgical
complications, as well as reoperation.
Previously identified risk factors for adverse events after
neck dissection include tumor stage, operative duration, and
major reconstruction.7,15 The NSQIP does not track tumor
stage but instead has a variable for ‘‘disseminated cancer’’;
this variable was not associated with adverse events of any
type. We also found a number of previously unidentified
factors associated with adverse events, including chronic
steroid use/immunosuppression, preoperative radiotherapy
within 90 days of the index procedure, chemotherapy within
30 days of the index procedure, dyspnea, COPD, advanced
age, and ASA classes 3 to 5. Each of these factors has
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75
Table 3. Thirty-Day Adverse Events vs Neck Dissection Cohort
(Univariate Analysis).
Clean,
No. (%)
Table 4. Multivariable Regression Analysis for Factors Associated
with Surgical Complications after Neck Dissection.a
Contaminated,
No. (%)
P Value
Surgical complications
All SSIs
Superficial SSI
94 (1.06)
Deep SSI
39 (0.44)
Organ/space SSI
14 (0.16)
Wound disruption
50 (0.56)
Medical complications
Pneumonia
99 (1.11)
Unplanned intubation
73 (0.82)
PE
17 (0.19)
Ventilator .48 h
79 (0.89)
Renal insufficiency
6 (0.07)
Acute renal failure
4 (0.04)
UTI
43 (0.48)
Peripheral neurologic deficit 16 (0.18)
Cardiac arrest
15 (0.17)
Blood transfusion
195 (2.19)
DVT
22 (0.25)
Systemic sepsis
59 (0.66)
Septic shock
15 (0.17)
MI
18 (0.20)
Stroke
9 (0.10)
Coma
5 (0.06)
Mortality
21 (0.24)
37 (6.47)
16 (2.80)
3 (0.52)
24 (4.20)
.000a
.000a
.079
.000a
25 (4.37)
19 (3.32)
3 (0.52)
40 (6.99)
1 (0.17)
0 (0.00)
9 (1.57)
3 (0.52)
9 (1.57)
72 (12.59)
5 (0.87)
22 (3.85)
6 (1.05)
4 (0.70)
1 (0.17)
0 (0.00)
10 (1.75)
.000a
.000a
.117
.000a
.354
.779
.004a
.104
.000a
.000a
.021a
.000a
.001a
.041a
.464
.732
.000a
Neck dissection cohort
Clean
Contaminated
Smoker
Excess alcohol intake
Steroid use
Preoperative radiotherapy
Chemotherapy
Prior operation \30 days
Dyspnea
Hypertension requiring
medication
History of COPD
Previous PCI
Cerebrovascular accident
History of TIA
Disseminated cancer
ASA .3
Obesity (BMI .30)
Operative duration
Anesthesia duration
Age
Odds
Ratio
95%
CI
P
Value
1 [reference]
3.422
1.152
0.758
0.834
2.326
0.82
0.365
1.286
1.055
1.963-5.964
0.773-1.714
0.391-1.469
0.289-2.404
1.102-4.913
0.305-2.208
0.111-1.197
0.759-2.179
0.728-1.528
.000b
.487
.411
.736
.027b
.695
.096
.351
.777
0.479
1.242
1.520
0.440
1.303
1.483
0.959
1.000
1.003
1.007
0.208-1.104
0.621-2.483
0.566-4.086
0.099-1.959
0.787-2.158
0.99-2.221
0.661-1.389
0.998-1.003
1.001-1.006
0.994-1.02
.084
.540
.406
.281
.303
.056
.823
.950
.006b
.289
Abbreviations: DVT, deep venous thrombosis; PE, pulmonary embolism; SSI,
surgical site infection; MI, myocardial infarction; UTI, urinary tract infection.
a
Denotes significant value, P \.05.
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass
index; CI, confidence interval; COPD, chronic obstructive pulmonary disease; PCI, percutaneous intervention; TIA, transient ischemic attack.
a
Hosmer-Lemeshow test statistic of .215.
b
Denotes significant value, P \.05.
previously been identified as a predictor of adverse
events in other surgical settings but not in head and neck
surgery.16-30
Surgical complications identified in the NSQIP database
include SSI and wound disruption. Surgical site infection, as
defined in the NSQIP database, stratifies infection occurring
within 30 days after the operation into 3 categories: superficial wound infection, deep incisional infection, and organ
space infection. Superficial site infections require identification of purulent drainage or organisms isolated from aseptic
culture from fluid or tissue from the superficial incision
after the incision is opened by the surgeon. Deep infections
differ by involvement of fascia or muscle layers with either
spontaneous opening or deliberate opening by the surgeon
with symptoms including temperature over 38°C and pain.
Organ space infection involves any organ or space, other
than the incision, that was opened during an operation.
These rigorous, standardized definitions likely contribute to
the relatively low incidence of neck SSIs found in this study
(ie, 2% for clean and 9% for contaminated cases).
Although the current study is not able to evaluate this proposition, the role of prophylactic antibiotics in preventing SSI
in head and neck procedures has been extensively studied at
single institutions.3,8-10,14,15,31-35 The authors assume that
standard protocols for antibiotic prophylaxis in head and
neck procedures were used in recorded cases. It should be
noted, however, that the relatively low rate of surgical infection after neck dissections captured in the NSQIP data set (ie,
2%-9%, compared with 3%-28% in published literature) will
likely affect any such future studies on this subject.
Previous research has shown an increased risk of medical
complications, such as pneumonia, sepsis, respiratory failure,
and urinary tract infection (UTI) in head and neck surgical
procedures contaminated with oropharyngeal flora.8,9,36-41 In
contrast, our study did not find a significant association
between oropharyngeal contamination and medical adverse
events. Reasons for these discrepancies may include (1) a
lack of sufficient statistical power in previous studies, (2)
inconsistencies in adverse event identification in the postoperative period, and/or (3) errors in procedural tracking. In
light of these discrepancies, further research should be spent
examining these differences and whether they are due to data
collection or significant changes in patient care that have
decreased medical morbidity associated with contaminated
neck dissections.
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76
Otolaryngology–Head and Neck Surgery 153(1)
Table 5. Multivariable Regression Analysis for Factors Associated
with Medical Complications after Neck Dissection.a
Odds
Ratio
Neck dissection cohort
Clean
Contaminated
Smoker
Excess alcohol intake
Steroid use
Preoperative radiotherapy
Chemotherapy
Prior operation \30 days
Dyspnea
Hypertension requiring
medication
History of COPD
Previous PCI
Cerebrovascular accident
History of TIA
Disseminated cancer
ASA .3
Obesity (BMI .30)
Operative duration
Anesthesia duration
Age
95%
CI
P
Value
1 [reference]
0.953
1.193
1.187
2.087
1.103
2.303
0.997
1.497
1.061
0.644-1.411
0.912-1.56
0.797-1.767
1.239-3.514
0.608-2.002
1.296-4.093
0.592-1.679
1.073-2.087
0.834-1.349
.810
.198
.398
.006b
.748
.004b
.992
.017b
.631
1.59
1.028
1.316
1.051
0.994
1.705
0.897
1.001
1.004
1.029
1.056-2.394
0.663-1.594
0.667-2.597
0.55-2.01
0.699-1.413
1.305-2.228
0.701-1.148
0.999-1.002
1.002-1.006
1.02-1.038
.026b
.902
.428
.880
.972
.000b
.388
.526
.000b
.000b
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass
index; CI, confidence interval; COPD, chronic obstructive pulmonary disease; PCI, percutaneous intervention; TIA, transient ischemic attack.
a
Hosmer-Lemeshow test statistic of .061.
b
Denotes significant value, P \.05.
Staged neck dissection has demonstrated efficacy in a
number of clinical scenarios and could decrease the risk of
oropharyngeal contamination. These include transoral surgery
for oropharyngeal cancer, in which there is an opportunity
for performing the neck dissection either before or after surgical excision of the primary tumor, and in patients treated
primarily with chemoradiation for advanced head and neck
cancer.42-46 In addition, surgeons could make efforts to separate oropharyngeal and neck dissection fields by minimizing
mucosal violation whenever possible. While these maneuvers
seem reasonable in early stage oral cancer, in advanced
cancer, the resection specimen is often contiguous with the
neck dissection, and thus separation of the 2 surgical sites is
impossible. While soft tissue flaps could be used to decrease
anatomic dead spaces, provide anatomic barriers, and
improve the vascularity of surgical beds, examination of such
techniques is beyond the scope of this article.
There are a number of limitations in our study. We did
not define the specific duration for the onset of complications from the time of surgery, nor did we identify if complications occurred pre- or postdischarge. Misclassification
of procedure CPT codes has been cited as a limitation of
the NSQIP database, although interobserver reliability is
Table 6. Odds Ratio Analysis for Contaminated Neck Dissection
vs Clean Neck Dissection (as Reference), Excluding All Cases
Involving Thyroidectomy (Current Procedural Terminology Codes
60210, 60212, 60220, 60225, 60240, 60252, 60254, 60260, 60270,
60271, 60500).
Surgical complications
Medical complications
Total complications
Reoperation
Readmission
Death
Odds Ratio
95% CI
P Value
2.333
0.871
1.056
1.868
0.907
0.782
1.25-4.355
0.583-1.302
0.727-1.535
1.199-2.911
0.331-2.486
0.17-3.595
.008a
.502
.775
.006a
.86
.752
Abbreviation: CI, confidence interval.
a
Denotes significant value, P \.05.
.98%.47 In addition, the study evaluates both specialists
and nonspecialists, as neck dissection is not necessarily performed by surgeons with oncologic surgical training. As has
been described in other studies, the NSQIP does not track
procedure-specific or specialty-specific outcomes and complications (eg, chyle leak, pharyngeal fistula, hemorrhage).
The authors defined ‘‘clean’’ vs ‘‘contaminated’’ cases
on the basis of CPT codes. While patients undergoing ‘‘contaminated’’ procedures had greater attendant presurgical
comorbidity than did patients undergoing ‘‘clean’’ procedures, multivariate analysis was used to control for those
variables with P \ .2 and n . 10 (Tables 3 and 4).19,20
Our method does not allow the head-to-head comparison of
specific procedures (as identified by CPT codes), since, for
example, all composite mandible resections are considered
‘‘dirty,’’ while all parotidectomies are considered ‘‘clean.’’
As a caveat, some patients with simple oral excisions (eg,
glossectomies) may not have been contaminated if there
was no direct communication with the neck dissection and
therefore may have been misclassified. Conversely, some
‘‘clean’’ cutaneous or salivary lesions (eg, parotidectomies)
may have been contaminated if there was violation of the
oral mucosa. While there are a number of options to clarify
these inconsistencies (eg, using concurrent free flap codes
to identify cases where oral mucosa was violated), such
analyses were not performed.
Finally, we attempted to focus on oropharyngeal (as
opposed to laryngeal and respiratory) contamination by removing those patients with laryngectomies as their sole extirpative
surgery. However, it is still possible to have respiratory contamination from cases undergoing pharyngolaryngectomies
and/or concomitant tracheostomy, and there is no feasible way
to discriminate the source of contamination in the NSQIP.
Regardless of these limitations, the current study helps to
define the relationship between oropharyngeal contamination and adverse events after neck dissection. It should be
used for individual patient risk stratification by providers,
health care monitoring agencies, and payors to subgroup
those patients undergoing ‘‘contaminated’’ neck dissection
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Jain et al
77
procedures into a category with an expected increased risk
of postoperative adverse events (specifically, 2-3 times
above baseline risk). Similarly, patients can be informed
that their particular surgery may confer significantly elevated risk of surgical adverse events and reoperation compared with ‘‘clean’’ neck dissections. In an era of consumerdriven health care, whether these factors will drive patients
to seek less invasive techniques (eg, trans-oral robotic surgery [TORS] chemoradiation), remains to be seen. Future
study should focus on evaluating (1) the length of antibiotic
administration for oropharyngeal exposure during neck dissection; (2) the relationship between preexisting infection,
dentition status, dental extraction, and infection; and (3) the
feasibility of separating neck dissection from oropharyngeal
extirpation (eg, subgroup analysis of patients undergoing
composite mandible resection with immediate vs delayed
neck dissection). As the NSQIP data set continues to
evolve, these analyses should be feasible.
3.
4.
5.
6.
7.
Authors’ Note
The NSQIP and the hospitals participating in the NSQIP are the
source of the data used herein; they have not been verified and are
not responsible for the statistical validity of the data analysis or the
conclusions derived by the authors of this study. De-identified patient
information is freely available to all institutional members who
comply with the American College of Surgeons National Surgical
Quality Improvement Program (NSQIP) Data Use Agreement. The
Data Use Agreement implements the protections afforded by the
Health Insurance Portability and Accountability Act of 1996.
8.
9.
10.
11.
Author Contributions
Umang Jain, study design, data analysis, drafting, revision manuscript, final approval of manuscript, accountable for all aspects of
the work; Jessica Somerville, study design, data analysis, drafting,
revision manuscript, final approval of manuscript, accountable for
all aspects of the work; Sujata Saha, study design, data analysis,
drafting, revision manuscript, final approval of manuscript, accountable for all aspects of the work; Nicholas James Hackett, study
design, data analysis, drafting, revision manuscript, final approval of
manuscript, accountable for all aspects of the work; Jon P. Ver Halen,
study design, data analysis, drafting, revision manuscript, final approval
of manuscript, accountable for all aspects of the work; Anuja K.
Antony, study design, data analysis, drafting, revision manuscript, final
approval of manuscript, accountable for all aspects of the work;
Sandeep Samant, study design, data analysis, drafting, revision manuscript, final approval of manuscript, accountable for all aspects of the
work.
12.
13.
14.
15.
16.
Disclosures
Competing interests: None.
Sponsorships: None.
17.
Funding source: None.
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