Impact of preoperative body mass index and weight loss on morbidity and mortality following colorectal cancer—a retrospective cohort study

Purpose Body weight and preoperative weight loss (WL) are controversially discussed as risk factors for postoperative morbidity and mortality in colorectal cancer surgery. The objective of this study is to determine whether body mass index (BMI) or WL is associated with a higher postoperative complication rate. Methods In this retrospective cohort study, data analysis of 1241 consecutive patients undergoing colorectal cancer surgery in an 11-year period was performed. The main outcome measures were wound infections (WI), anastomotic leakages (AL), and in-house mortality. Results A total of 697 (56%) patients with colon and 544 (44%) with rectum carcinoma underwent surgery. The rate of WI for each location increased with rising BMI. The threshold value was 28.8 kg/m 2 . Obese patients developed significantly more WI than normal-weight patients did following rectal resection (18.0% vs. 8.2%, p = 0.018). Patients with preoperative WL developed significantly more AL following colon resections than did patients without preoperative WL (6.2% vs. 2.5%, p = 0.046). In-house mortality was significantly higher in obese patients following colon resections than in overweight patients (4.3% vs. 0.4%, p = 0.012). Regression analysis with reference to postoperative in-house mortality revealed neither increased BMI nor WL as an independent risk factor. Conclusions Increased preoperative BMI is associated with a higher WI rate. AL rate after colon resection was significantly higher in patients showing preoperative WL. Preoperative BMI and WL are therefore risk factors for postoperative morbidity in this study. Nevertheless, this has to be further clarified by means of prospective studies. Trial registration DRKS00025359, 21.05.2021, retrospectively registered.