Body mass index: Implications on disease severity and postoperative complications in patients with Crohn's disease undergoing abdominal surgery

Background: Obesity is increasing in prevalence among patients with Crohn's disease, but how body mass index affects disease severity and postoperative outcomes remains unknown. Methods: A retrospective review of ileocolic resections for Crohn's disease performed at a single institution between January 2007 and December 2017 was conducted. On the day of surgery, patients were grouped by body mass index into underweight, normal weight, overweight, and obese categories. Intergroup comparisons and trend tests were performed on disease characteristics and postoperative outcomes. A multivariable model for superficial surgical site infection was constructed. Results: A total of 758 patients were identified; 80 (11%) patients were underweight, 372 (49%) were normal weight, 178 (23%) were overweight, and 128 (17%) were obese. Both fistulizing Crohn's phenotype and preoperative immunosuppression occurred less frequently in obese patients compared with other body mass index groups (both P < 0.01). Conversion to open surgery and superficial surgical site infection were increased in obese patients, and obesity was an independent risk factor for superficial surgical site infection on multivariable analysis (odds ratio 3.0, 95% confidence interval: 1.6–5.6). Conclusion: Although obese patients had less severe Crohn's disease at the time of surgery, they experienced increased postoperative infectious complications. Preoperative weight loss and consideration of alternative wound closure methods may reduce these complications.