Short-term Complication Rates Following Anterior Urethroplasty: An Analysis of National Surgical Quality Improvement Program Data

Short-term Complication Rates Following Anterior Urethroplasty: An Analysis of National Surgical Quality Improvement Program Data

Accepted Manuscript Title: Short-Term Complication Rates Following Anterior Urethroplasty: an Analysis of NSQIP Data Author: JM Lacy, RJ Madden-Fuente...

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Accepted Manuscript Title: Short-Term Complication Rates Following Anterior Urethroplasty: an Analysis of NSQIP Data Author: JM Lacy, RJ Madden-Fuentes, A Dugan, AC Peterson, S Gupta PII: DOI: Reference:

S0090-4295(17)30801-4 http://dx.doi.org/doi: 10.1016/j.urology.2017.08.006 URL 20600

To appear in:

Urology

Received date: Accepted date:

22-5-2017 2-8-2017

Please cite this article as: JM Lacy, RJ Madden-Fuentes, A Dugan, AC Peterson, S Gupta, ShortTerm Complication Rates Following Anterior Urethroplasty: an Analysis of NSQIP Data, Urology (2017), http://dx.doi.org/doi: 10.1016/j.urology.2017.08.006. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

1 Short-Term Complication Rates Following Anterior Urethroplasty: An Analysis of NSQIP Data Lacy JM1, Madden-Fuentes RJ2, Dugan A3, Peterson AC2, Gupta S3 1

University of Tennessee Health Sciences Center Graduate School of Medicine, Division of Urology, Knoxville, TN 2

Duke University Medical Center, Department of Surgery, Division of Urology, Durham, North Carolina 3

University of Kentucky Medical Center, Department of Urology, Lexington, Kentucky

Corresponding Author John M. Lacy, MD University of Tennessee Health Sciences Center Graduate School of Medicine Division of Urology 1928 Alcoa Hwy, B-222 Knoxville, TN Phone: 865-305-9254 Fax: 865-305-4589 Keywords: urethroplasty, NSQIP, urethral stricture, surgical morbidity, buccal mucosal graft Author contact information: John Lacy: [email protected] Ramiro Joe Madden-Fuentes: [email protected] Adam Dugan: [email protected] Andrew Peterson: [email protected] Shubham Gupta: [email protected] Manuscript word count: 2351 Abstract word count: 235

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2 Abstract Objective: To determine the characteristics and predictors of perioperative complications after male anterior urethroplasty. Materials and Methods: American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a validated outcomes-based program comprising academic and community hospitals in the United States and Canada. Data from 2007-2015 were queried for single-stage anterior urethroplasty using Current Procedure Terminology (CPT) codes. The primary outcome was frequency of complications within the 30-day postoperative period. Preoperative and intraoperative parameters were correlated with morbidity measures and univariate and multivariate regression analyses were used. Results: 556 patients underwent anterior urethroplasty, of whom 180 (32.4%) had graft/flap placement. 127 patients (22.9%) went home the same day after surgery, 255 patients (45.9 %) stayed 1 night, and 173 (31.2%) stayed for 2 or more nights. No deaths, cardiovascular complications, or sepsis were noted. 47 (8.5%) patients had complications in the 30-day period. The most common complications were infection (57.4%), readmission (42.9%) and return to the operating room (17%). On univariate analysis, patients who had substitution urethroplasty (p=0.04) and longer operative times (p=0.002) were more likely to have complications, but only longer operative time showed significance on multivariate analysis (p=0.006). Age, American Society of Anesthesiologists (ASA) score and length of stay were not predictive of complication frequency. Conclusions: Anterior urethroplasty has low postoperative morbidity. Longer operative times were associated with increased rate of complications. Longer hospital stay after surgery is not protective against perioperative complications.

Introduction Urethral stricture disease has a poorly defined prevalence due to under recognition in the ambulatory setting. Large dataset reports including the National Inpatient Sample (NIS), private and public health care bases, and the Veterans Affairs Corporate Data Warehouse highlight that the prevalence of urethral stricture disease is significant. The rate is as high at 0.6% in some populations and the cost of urethral stricture disease has been suggested to be almost $200 million. (1) Between October 1999 and August 2013, there were

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3 92,448 procedure performed to manage urethral stricture disease in the veteran population.(2) Similarly, the NIS revealed that between 2000 and 2010, 13,700 urethroplasty procedures were performed in the United States.(3) The success rates of anterior urethroplasty are high and complications infrequent.(3) Most of the available data regarding outcomes, including both success rates and complications, are gleaned from retrospective single institution series. A prospective analysis of patient outcomes is largely lacking in the published literature for this clinical entity. These lack of data may contribute to a barrier to care for older patients with multiple comorbidities that are only offered temporizing treatments for urethral stricture disease as opposed to definitive urethral reconstruction. The National Surgical Quality Improvement Program supported by the American College of Surgeons (ACS- NSQIP), prospectively collects data regarding surgical outcomes. This database encompasses data collected from a growing cohort of hospitals/hospital systems within the United States. With this high-quality, multi-center registry, we aimed to identify and compare the 30-day complication rates of patients undergoing urethroplasty in an effort to determine the strongest predictors of post-operative complications. Materials and Methods This study was exempt from Institutional Review Board (IRB) approval. The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) was used to identify patients who had undergone urethroplasty between 2007 and 2015. The database was queried for anterior

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4 urethroplasty using Current Procedure Terminology (CPT) code 53410. Among these patients, the use of tissue transfer with flaps and/or grafts was identified using the CPT codes 14040, 14041, 15240, 15740, 20926, 40818 or 41870. Trained reviewers who abstract data from clinical charts in a standardized format prospectively collect data points. The dataset has over 250 collected variables that include preoperative risk factors, operative variables, and postoperative outcomes. The specifics of the ACS-NSQIP program and its data collection methods have been previously described.(4) Hospitals participating in the ACSNSQIP are given access to Participant Use Data Files (PUFs), an aggregate collection of data without site or patient identification intended to promote research and advance the quality of patient care. These data were used to evaluate our primary endpoint of any short-term postoperative complication deemed major morbidities, including: any readmission, any return to the operating room, transfusion within 72 hours of surgery, myocardial infarction, cardiac arrest, reintubation, failure to wean, graft failure, pneumonia, infection (urinary tract infection, surgical site infection [superficial, deep, or organ/space], wound dehiscence, sepsis, or septic shock), treated deep venous thrombosis or pulmonary embolism, renal insufficiency, or acute renal failure. Further information on the definition of urinary tract infection in this dataset is included as an appendix. The NSQIP dataset includes all patients over 18 years of age at participating hospitals and tracks age up to 90 years old. After 90 years old, the pati ent’s age is recorded as 90 plus for privacy reasons.

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5 Preoperative and intraoperative variables were compared using Chi-square, Fisher’s exact, Mann-Whitney U, and Kruskall-Wallis tests, as appropriate. Forward stepwise multivariable logistic regression (p for entry < .05, for exit > .10) was performed to identify strong independent predictors of major morbidity. Significance was set at p < 0.01 due to multiple comparisons. All analyses were performed in R (version 3.2.0; R Core Team, Vienna, Austria). Results From 2007 – 2015, the number of urethroplasties captured in the NSQIP dataset has increased (Appendix 1). In total, 556 patients underwent anterior urethroplasty during the study period, 180 (32.4%) of whom had substitution urethroplasty with the use of flaps/grafts. There were no cases of death, cardiovascular complication, or severe sepsis reported within 30 days of surgery within the entire cohort of 556 patients. The primary endpoint was frequency of major morbidity as defined in the methods section above. Major morbidity was noted in 47/556 patients (8.5%). Perioperative characteristics of patients who experienced major morbidity are summarized in Table 1. The most common complications were infection – either surgical site infection or urinary tract infection - (57.4%), followed by readmission (42.9%) and return to the operating room (17%). Among infectious complications, urinary tract infection accounted for 17 patients (36.2%) while surgical site infection occurred in 10 patients (21.3%). There were no preoperative variables associated with experiencing postoperative morbidity including age, ASA score, BMI, diabetes, smoking, salient laboratory values, and steroid use. Patients who

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6 experienced morbidity were more likely to have use of grafts/flaps (22/47, 46.8%) compared to those who did not have complications (158/509, 31%; p =0.041). Additionally, patients experiencing major morbidity had longer operative times (mean 208 minutes versus 165 minutes, p =0.002) compared to those without morbidity (Table 1). Overall, 127 patients (22.9%) were discharged the day of surgery, 255 (45.9%) stayed one night in the hospital, while 173 (31.2%) stayed 2 or more nights. Longer operative times as well as the use of grafts/flaps were associated with a longer length of stay. Overall postoperative morbidity was similar among patients who went home the same day (6.3%), who stayed 1 day (8.2%), and those who stayed 2 or more days (10.4%) (p =0.444). Use of Grafts/Flaps 180 (32.4%) patients underwent urethroplasty with a flap/graft repair. Comparison of the preoperative factors including age, BMI, diabetes, smoking, and steroid use were not statistically different between patients undergoing urethroplasty with or without a flap/graft repair. On univariate analysis, the use of graft/flap in the repair was associated with a higher risk of a major morbidity (12.2% vs 6.6%, p=0.04). The group that underwent grafts/flaps demonstrated longer operative times (211 vs 149 minutes, p=<0.01), and stayed longer in the hospital after surgery (Table 2). Subgroup analyses in the graft/flap cohort demonstrated that there was no difference in morbidity between patients who were discharged the day of surgery versus those that stayed longer. Further

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7 analyses comparing LOS < 2 days versus LOS ≥ 2 days noted similar lack of difference in morbidity (Table 3). Age and ASA Score Bivariate analyses were conducted to see if Age 65 years was associated with perioperative variables (Appendix 2). Patients 65 years or older comprised 16% (89 patients) of the cohort. Older patients were less likely to receive grafts/flaps (16.9% versus 35.3%, p =0.001), and correspondingly had shorter operative times as compared to younger patients (143 minutes versus 174 minutes, p =0.001). Older patients were more likely to be discharged the same day as surgery compared to younger patients (38.2% versus 20%, p <0.001). Overall, 11.2% of older patients experience major morbidity compared to 7.9% in the younger cohort (p = 0.411). Sub-categories of major morbidity did not differ between older and younger patients. 170 patients (30.6%) had an ASA category of III or higher. These patients were older compared to ASA I – II patients (mean age 57 years versus 43 years, p < 0.001), and were correspondingly more obese, and had more pre-existing comorbidities. In terms of intra- and post-operative variables, ASA Class III or higher had similar rates of grafts/flaps, length of stay, operative duration, and major morbidity as compared to ASA class I-II (Appendix 3). Multivariate Analysis Based on the results of the initial analysis, subgroup and regression analyses were performed (Table 5). Use of grafts/flaps, LOS >0, operative time (30 min increments), and age >65 years were used to construct a generalized

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8 linear model with a logit link function and binomial response. Each 30 minute increase in operative time was associated with a 17% increase in odds of major morbidity (OR 1.17, CI 1.04 -1.30, p =0.006). Length of stay, graft/flap use, and age did not have significantly increased odds of having major morbidity. Another model changing the LOS parameters as ≤1 day versus ≥2 days showed similar results (table 3b). A graph of the Chi-square test statistic for the association between morbidity and operation duration revealed 190 minutes as the most significant operative time cutoff. Patients with operative time less than or equal to 190 minutes had 5.7% major morbidity rate compared to 14% in patients having operative time of >190 minutes (p= 0.002) (Figure 1). Discussion In this analysis of prospectively collected outcomes after anterior urethroplasty, we find that the overall rate of complications is low (8.5%), even in patients who are older (>65 years) and with associated comorbidities. Our data show that operative time >190 minutes portends a higher risk of subsequent morbidity. In fact, we demonstrate that the odds of experiencing a major morbidity increased by 17% with each 30 minutes’ increase in operative time. It is probable that longer operative times are a surrogate for one or many other factors (stricture length, complexity, prior surgeries, surgeon experience etc.) that are not captured in this database. Notably, in our study length of hospitalization after urethroplasty did not correlate with either decreases or increases in subsequent morbidity, including

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9 readmission rates. Our results suggest that postoperative admission may not be necessary in patients undergoing urethroplasty. This observation has been supported by other reports, including a recent study by Macdonald et al that used an overlapping dataset from the NSQIP database.(6,7) Studies have reported on the satisfaction and safety of outpatient urethroplasty as well. In a study by Okafor and Nikolavsky, a validated questionnaire assessing health-related quality-of-life outcomes showed no differences between the groups in the dimensions of mobility, self-care, pain/discomfort, and anxiety. (8) The present analysis demonstrated an 8.5% rate of perioperative complications. These results are consistent with the known single center and multicenter retrospective analysis previously published (9-14). In a multiinstitutional retrospective analysis of men undergoing long stricture repair, early complications included UTI in 2.4%, wound dehiscence in 1.6% and pulmonary embolism in 1 patient (0.2%).(10) While the overall infection rate in our study was slightly higher, this may be explained by our additional reporting of surgical site infections, as our urinary tract infection rates were similar at 3%. In another cohort of 395 patients, 146 reported some perioperative complaint. Classification of all complications by Clavien-Dindo categories demonstrated grade I in 60%, grade II in 32%, grade III in 6%, grade IV in 2%, and grade V in 0%. (11) Our data show a return to the operating room (Clavien 3 complication) in 1.4% of overall patients, which compares favorably to these data. Eltahaway et al reported a series of 257 patients with early UTI rates as high as 5%, along with positional neuropraxia (3.4%), chest infection (1.9%), scrotalgia (1.5%) and

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10 wound complications (1.5%). (13) While these data are heterogeneous and retrospective, our study supports the notion that morbidity following urethroplasty is low and is in line with other reported studies. Outcomes in older patient populations (>65 years old) have also been reported. In a report of 70 patients with a mean age of 71 years, the rate of complications - specifically scrotal hematoma, wound dehiscence and pulmonary edema - were 1-3%. In this cohort, there was also one death due to unknown causes. (16) The NIS cohort reported an overall complication rate of 6.6%, with genitourinary complications accounting for 2.8% of these. In this study, the complication rate was higher in men >65 years old when compared to 18-45 year old men (11.6% vs. 3.9%, respectively).(3) We did not see a difference in complication rates between the patients younger than 65 years old compared to those greater than 65 years old. We did note that older men were less likely to receive substitution urethroplasty, and correspondingly had shorter operative times, and shorter hospital stay. This finding is in agreement with the results of a survey that demonstrated that more reconstructive urologists preferred excision and primary anastomosis in older men as compared to younger men with the same stricture length. (17) This may be related to diminished concern about preservation of erectile function in this population, allowing surgeons to be more aggressive with anastomotic urethroplasty. This may have confounded our univariate analysis results; therefore, we included patient age in our multivariate model which did not show significantly increased morbidity in the elderly.

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11 There is increasing attention in the scientific community on perioperative complications, reducing readmission, and improving patient satisfaction. CMS already incentivizes reduction in readmission and complications after certain medical diagnosis discharges and in the future a penalty for meeting certain benchmark numbers may be expected.(18) Additionally, there is growing public awareness of perioperative outcomes and complications after commonly performed surgeries. Using medical claims data, propublica.org published their analysis of individual surgeon complications for certain procedures, including prostatectomy and TURP. (19) While their methodology and results have several scientific limitations and have been criticized by the scientific community at large, it is a harbinger of the inevitable scrutiny that surgeons will continue to face from the public and policymakers. Conclusions ascertained from this data source are limited by the inherent limitations of the NSQIP database. (20,21) The details surrounding each admission are less available than chart review and we are unable to provided key components such as surgeon experience, stricture length and caliber, presence of preoperative urinary tract infection, history of suprapubic tube, or number of previous interventions. Importantly, the NSQIP database is not longitudinal for privacy reasons. Therefore, if a patient had an additional procedure after the 30 days following their index case the database would capture that event as having occurred on a new, unrelated patient. This may lead to more complex cases and increase variables including operative time and risk of morbidity. Furthermore, there are also no standard recommendations for pre-, peri- and postoperative

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12 antibiotic coverage, or how long to keep catheters in place after surgery. These factors likely varied significantly at different sites and could further confound our data. Conclusion Anterior urethroplasty carries a low rate of morbidity and mortality. Longer operative times are associated with increased complication frequency. Complication rates do not differ based on age, patient comorbidity or hospital length of stay.

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13 References 1.Santucci RA, Joyce GF, Wise M. Male urethral stricture disease. J Urol. 2007;177(5):1667-74. 2.Lacy JM, Cavallini M, Bylund JR, Strup SE, Preston DM. Trends in the management of male urethral stricture disease in the veteran population. Urology. 2014;84(6):1506-9. 3.Blaschko SD, Harris CR, Zaid UB, Gaither T, Chu C, Alwaal A, et al. Trends, utilization, and immediate perioperative complications of urethroplasty in the United States: data from the national inpatient sample 2000-2010. Urology. 2015;85(5):1190-4. 4.Hall BL, Hamilton BH, Richards K, Bilimoria KY, Cohen ME, Ko CY. Does surgical quality improve in the American College of Surgeons National Surgical Quality Improvement Program: an evaluation of all participating hospitals. Ann Surg. 2009;250(3):363-76. 5.Wessells H, Angermeier KW, Elliott S. Male Urethral Stricture: American Urological Association Guideline. J Urol. 2017 Jan;197(1):182-190. 6. MacDonald S, Haddad D, Choi A, Colaco M, Terlecki R. Anterior Urethroplasty Has Transitioned to an Outpatient Procedure Without Serious Rise in Complications: Data From NSQIP. Urology. 2016. 7.Theisen K, Fuller TW, Bansal U, et al. Safety and Surgical Outcomes of Sameday Anterior Urethroplasty. Urology. 2017 Apr;102:229-233. 8. Okafor H, Nikolavsky D. Impact of Short-Stay Urethroplasty on Health-Related Quality of Life and Patient's Perception of Timing of Discharge. Adv Urol. 2015;2015:806357. 9.Santucci RA, Mario LA, McAninch JW. Anastomotic urethroplasty for bulbar urethral stricture: analysis of 168 patients. J Urol. 2002;167(4):1715-9. 10.Warner JN, Malkawi I, Dhradkeh M, et al. A Multi-institutional Evaluation of the Management and Outcomes of Long-segment Urethral Strictures. Urology. 2015;85(6):1483-7. 11.Granieri MA, Webster GD, Peterson AC. Critical Analysis of Patient-reported Complaints and Complications After Urethroplasty for Bulbar Urethral Stricture Disease. Urology. 2015;85(6):1489-93. 12. Bascom A, Ghosh S, Fairey AS, et al. Assessment of Wound Complications After Bulbar Urethroplasty: The Impact of a Lambda Perineal Incision. Urology. 2016 Apr;90:184-8. 13. Eltahawy EA, Virasoro R, Schlossberg SM, McCammon KA, Jordan GH. Long-term followup for excision and primary anastomosis for anterior urethral strictures. J Urol. 2007;177(5):1803-6. 14.Kessler TM, Schreiter F, Kralidis G, Heitz M, Olianas R, Fisch M. Long-term results of surgery for urethral stricture: a statistical analysis. J Urol. 2003;170(3):840-4. 15.Martinez-Pineiro JA, Carcamo P, Garcia Matres MJ, Martinez-Pineiro L, Iglesias JR, Rodriguez Ledesma JM. Excision and anastomotic repair for urethral stricture disease: experience with 150 cases. Eur Urol. 1997;32(4):433-41.

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14 16.Santucci RA, McAninch JW, Mario LA, et al. Urethroplasty in patients older than 65 years: indications, results, outcomes and suggested treatment modifications. J Urol. 2004;172(1):201-3. 17. Lacy JM, Johnson S, Dugan A, et al. Urethroplasty Practice Patterns of Genitourinary Reconstructive Surgeons. http://dx.doi.org/10.1016/j.urpr.2017.04.001. 18. Lu N, Huang KC, Johnson JA. Reducing excess readmissions: promising effect of hospital readmissions reduction program in US hospitals. Int J Qual Health Care. 2016;28(1):53-8. 19. Rosenbaum L. Scoring No Goal--Further Adventures in Transparency. N Engl J Med. 2015;373(15):1385-8. 20.Sellers MM, Merkow RP, Halverson A, et al. Validation of new readmission data in the American College of Surgeons National Surgical Quality Improvement Program. J Am Coll Surg. 2013;216(3):420-7. 21.Steinberg SM, Popa MR, Michalek JA, Bethel MJ, Ellison EC. Comparison of risk adjustment methodologies in surgical quality improvement. Surgery. 2008;144(4):662-7; discussion -7.

Figure 1. Chi-square test to assess association between morbidity and operative duration reveals increased complication rates in operations >190 minutes (p= 0.002).

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15 Table 1 : Patient Characteristics by Major Morbidity Major P-Value Morbidity 509 (91.5%) 47 (8.5%) 47 (16) 47 (17) 0.986 None

Number of Cases Mean Age (SD), years ASA Class ASA I-II ASA III+ BMI, kg/m2 ≤ 18.5 18.51 - 25.00 25.01 - 30.00 30.01 - 35.00 35.01 - 40.00 40.01+ Treatment for Diabetes Current Smoker Treatment for Hypertension Steroid use for Chronic Condition Bleeding Disorder Creatinine > 1.2 mg/dL WBC ≤ 4,500/mm3 WBC > 11,000/mm3 HCT > 45% Platelets < 150,000/mm3 Graft or Flap Used

353 (69.4%) 156 (30.6%) 8 (1.9%) 75 (17.6%) 155 (36.4%) 105 (24.6%) 48 (11.3%) 35 (8.2%) 69 (13.6%) 82 (16.1%) 173 (34.0%)

2 (5.3%) 8 (21.1%) 9 (23.7%) 10 (26.3%) 5 (13.2%) 4 (10.5%) 6 (12.8%) 8 (17.0%) 18 (38.3%)

1.000

0.397

1.000 1.000 0.664

12 (2.4%)

1 (2.1%)

1.000

6 (1.2%) 76 (21.1%) 28 (7.7%) 21 (5.8%) 91 (24.9%) 25 (6.9%)

1 (2.1%) 6 (18.2%) 4 (11.8%) 2 (5.9%) 9 (26.5%) 3 (8.8%) 22 (46.8%) 17 (36.2%)

0.463 0.869 0.339 1.000 1.000 0.723

158 (31.0%)

Outpatient

207 (40.7%)

Length of Hospital Stay 0

119 (23.4%)

1

234 (46.1%)

2+

155 (30.5%)

Duration of Operation, Mean Minutes (SD) Any Readmission

33 (70.2%) 14 (29.8%)

8 (17.0%) 21 (44.7%) 18 (38.3%)

0.041 0.656

0.444

165 (81)

208 (97)

0.002

0 (0.0%)

18 (42.9%)

<0.001

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16 Any Return to OR Pulmonary Embolism or Deep Venous Thrombosis Any Infection UTI SSI Sepsis/Septic Shock

0 (0.0%)

8 (17.0%)

<0.001

0 (0.0%)

3 (6.4%)

<0.001

0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)

27 (57.4%) 17 (36.2%) 10 (21.3%) 0 (0.0%)

<0.001 <0.001 <0.001 N/A

Table 2: Perioperative Characteristics by Graft/Flap Use None Graft/Flap Length of Hospital Stay 0 1 2+ Duration of Operation, Mean Minutes (SD) Major Morbidity Any Readmission Any Return to OR Pulmonary Embolism or Deep Venous Thrombosis Any Infection UTI SSI Sepsis/Septic Shock

P-Value

106 (28.2%) 174 (46.3%) 96 (25.5%)

21 (11.7%) 81 (45.3%) 77 (43.0%)

149 (76)

211 (81)

<0.001

25 (6.6%) 10 (3.6%) 6 (1.6%)

22 (12.2%) 8 (5.0%) 2 (1.1%)

0.041 0.666 1

2 (0.5%)

1 (0.6%)

1

14 (3.7%) 9 (2.4%) 5 (1.3%) 0 (0.0%)

13 (7.2%) 8 (4.4%) 5 (2.8%) 0 (0.0%)

0.113 0.293 0.306 N/A

<0.001

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17 Table 3. 3a. Comparison of morbidity rates by length of stay (LOS) in patients receiving a graft or a flap 3b. Comparison of morbidity rates by length of stay (LOS) in patients receiving a graft or a flap 3a.

Number of Cases No Major Morbidity At Least 1 Major Morbidity

LOS = 0, N (%)

LOS ≥ 1, N (%)

22 (12.2%) 20 (90.9%)

158 (87.8%) 138 (87.3%)

2 (9.1%)

20 (12.7%)

P-value*

1

3b. Comparison of morbidity rates by length of stay (LOS) in patients receiving a graft or a flap

Number of Cases (%) Morbidity No Major Morbidity At Least 1 Major Morbidity

LOS ≤ 1 d, N (%)

LOS ≥ 2, N (%)

103 (57.2%)

77 (42.8%)

90 (87.4%)

68 (88.3%)

13 (12.6%)

9 (11.7%)

P-value*

1

*Significance is determined used Fisher’s Exact test

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