Impact of BMI on Adverse Events After Laparoscopic and Open Surgery for Rectal Cancer

Purpose The impact of body mass index (BMI) on outcomes after open or laparoscopic surgery for rectal cancer remains unclear. The objective of this retrospective cohort study was to examine the interaction of body mass index and surgical modality (i.e., laparoscopy versus open) with respect to short-term clinical outcomes in patients with rectal cancer. Methods The ACS-NSQIP database (2012–2016) was reviewed for patients undergoing open or laparoscopic surgery for rectal cancer. The primary outcome was 30-day all-cause morbidity. Logistic regression and Cox proportional hazard models were used for analysis. Results A total of 16,145 patients were grouped into open ( N = 6759, 42%) and laparoscopic ( N = 9386, 58%) cohorts. Patients with higher BMI ( p < 0.001) and those undergoing open surgery ( p < 0.001) were at increased risk of all-cause morbidity. There was no significant change in the odds ratio of experiencing all-cause morbidity between open and laparoscopic surgery with increasing BMI ( p = 0.572). Median length of stay was significantly shorter in the laparoscopy group (4 days vs. 6 days; p < 0.001), at the cost of increased operative time (239 min vs. 210 min, p < 0.001). The difference in operative time between laparoscopy and open surgery did not increase with rising BMI (i.e., ∆37 min vs. ∆39 min at BMI 25 kg/m 2 vs 50 kg/m 2 , respectively, p = 0.491). Conclusion BMI may not be a strong modifier for surgical approach with respect to short-term clinical outcomes in patients with obesity and rectal cancer. Laparoscopic surgery was associated with improved short-term clinical outcomes, without much change in the absolute difference in operative time compared with open surgery, even at higher BMIs.