The relationship between body mass index, sex, and postoperative outcomes in patients undergoing potentially curative surgery for colorectal cancer

Abstract

Background: There is increasing evidence that an increased BMI is associated with increased complications after surgery for colorectal cancer (CRC). However, the basis of this relationship is not clear. Since men and women have different fat distribution, with men more likely to have excess visceral fat in BMI defined obesity, there may be a sex difference in the surgical site infection (SSIs) rate in the obese. Therefore, the aim of this study was to examine the relationship between sex, BMI, clinic-pathological characteristics and the development of postoperative infective complications after surgery for CRC and to establish whether there were gender differences in complication following surgery for CRC.

Design: Data were recorded prospectively for patients undergoing potentially curative surgery for CRC in a single centre between 1997 and 2016. Patient characteristics were recorded and complications were classified as either infective or non-infective. The relationship between sex, BMI, associated clinicopathological characteristics and presences of complications were examined by Chi-square test for linear association and multivariate binary logistic regression model.

Results: A total of 1039 patients were included. There were significant differences in the presence of complications between male and female (p ≤ 0.001), the rate of complication was higher in obese male (44%); in particular SSIs, wound infection and anastomotic leak (p ≤ 0.05). The rate of surgical site infection was 12% in male patients with normal BMI compared with 26% in those with a BMI ≥30 (p ≤ 0.001), while the rate of SSIs in female patients was 10% in those with normal BMI and those with a BMI ≥30. In males, BMI remained significantly associated with SSI on multivariate analysis [(OR = 1.42, 95% CI 1.13-1.78) P = 0,002].

Conclusions: Obesity prior to surgery for CRC increases the risk of infective complications in both male and female. Increased BMI in male patients was associated greater risk of SSIs and wound infection compared to female patients. Male obese patients should be considered at high risk of developing post-operative infective complications.

Keywords: Body mass index; Gender; Obesity; Postoperative complication; Surgical site infection.