Post-operative complications after colorectal cancer surgery increased with higher BMI

INTRODUCTION: Because of conflicting evidence regarding overweight and post-operative complications, this study focused on post-operative complications and death within 30 and 90 days after curatively intended surgery for colorectal cancer and its association with BMI.

METHODS: The study included all patients who had potentially curative surgery for colon or rectum cancer in Denmark from 2014 through 2018. The primary endpoint was post-operative complications within 30 days of surgery and secondary endpoints were 30- and 90-day mortality. All clinically relevant confounders were included in a multivariate analysis.

RESULTS: The cohort included 14,004 patients. In the multivariate logistic regression analysis, adjusting for relevant confounders, we found the odds ratio of having a surgical complication or having both a surgical and medical complication at the same time to be rising with increasing weight class. The multivariate analysis showed the odds ratio for both 30- and 90-day mortality to be higher for underweight patients and for obesity class III patients, but the rest of the patients had no significant differences in relative risk compared with normal-weight patients.

CONCLUSION: Based on our results, the risk of post-operative complications rises with increasing weight, whereas post-operative morbidity is increased only in the underweight and morbidly obese patients.

FUNDING: none.

TRIAL REGISTRATION: The study was approved by the Danish Data Protection Agency (REG-008-2020).