Effect of Body Mass Index on Outcomes After Surgery for Perforated Diverticulitis

Abstract

Background: Despite the increased adoption of minimally invasive techniques in colorectal surgery, an open resection with ostomy creation remains an accepted operation for perforated diverticulitis. In the United States, there is an increase in the rates of both morbid obesity and diverticular disease. Therefore, we wanted to explore whether outcomes for morbidly obese patients with diverticulitis are worse than nonmorbidly obese patients after open colectomy for diverticulitis.

Materials and methods: Using the American College of Surgeons National Surgical Quality Improvement Program database from 2005 to 2015, we identified adults with emergent admission for diverticulitis (International Classification of Diseases, Ninth Revision, code 562.11) with evidence of preoperative sepsis and intraoperative contaminated/dirty wound classification, in which a resection with ostomy (Current Procedural Terminology codes 44141, 44143, or 44144) was performed. We excluded cases with age >90 y, ventilator dependence, evidence of disseminated cancer and missing sex, race, body mass index, functional status, American Society of Anesthesiologists class, length of stay (LOS), or operative time data. Morbid obesity was defined as body mass index >35 kg/m². Risk variables of interest included age, sex, race, medical comorbidities, requirement for preoperative transfusion, preoperative sepsis, and operative time. Outcomes of interest included LOS, 30-d postoperative complications, and mortality. Univariate and propensity scores with postmatching analyses were performed.

Results: A total of 2019 patients met inclusion and exclusion criteria, of which 413 (20.5%) were morbidly obese. Morbidly obese patients tended to be younger (mean 57.2 versus 62.6 y) and female (54.5% versus 45.5%). Morbidly obese patients also had higher rates of insulin-dependent diabetes (8.0% versus 4.2%), hypertension (60.1% versus 51.3%), renal failure (3.4% versus 1.5%), and higher American Society of Anesthesiologists class (class 4: 23.5% versus 19.6% and class 5: 1.45% versus 0.87%). Morbidly obese patient had no increase in 30-d mortality or LOS, but they had higher rates of superficial wound infection (9.0% versus 5.8%; P = 0.0259), deep wound infection (4.4% versus 1.9%; P = 0.0073), acute renal failure (4.8% versus 2.4%; P = 0.0189), postoperative septic shock (17.7% versus 12.1%; P = 0.0040), and return to the operating room (11.1% versus 6.4%; P = 0.0015). We identified 397 morbidly obese patients well matched by propensity score to 397 nonmorbidly obese patients. Conditional logistic regression showed no difference in LOS (median 12.9 versus 12.4 d; P = 0.4648) and no increased risk of 30-d mortality (P = 0.947), but morbid obesity was an independent predictor for return to the operating room (adjusted odds ratio: 27.09 [95% confidence interval: 2.68-274.20]; P = 0.005).

Conclusions: This analysis of a large national clinical database demonstrates that morbidly obese patients presenting with perforated diverticulitis undergoing a Hartmann's procedure do not have increased mortality or LOS compared with nonobese patients. After adjusting for the effects of morbid obesity, morbidly obese patients had increased risk of return to operating room. Despite literature describing the many perioperative risks of obesity, our analysis showed only increased reoperation for obese patients with diverticulitis.

Keywords: Morbid obesity; NSQIP; Perforated diverticulitis.