Impact of visceral obesity on operative outcomes of laparoscopic nephrectomy: comparison between visceral fat area and body mass index

Abstract

Background: Obesity has been considered as a risk factor influencing operative difficulty. It was reported that body mass index (BMI; kg/m2) did not always properly reflect the degree of a patient’s visceral fat. The purpose of this study is to retrospectively investigate the association of operative outcomes and obesity indices including visceral fat area (VFA; cm2) and BMI in retroperitoneoscopic nephrectomy (RN). Methods: We retrospectively reviewed consecutive 96 RN procedures performed from September 2016 to June 2020. We divided patients into BMI obese group (BMI ≥ 25, n = 25) and BMI normal group (BMI < 25, n = 71), VFA obese group (VFA ≥ 100, n = 54) and VFA normal group (VFA < 100, n = 42). Patient characteristics, operative and postoperative outcomes were compared between the two groups for each index of obesity. Results: In two groups divided by BMI, the only specimen weight was significantly greater in the obese group (320 vs. 460 g, p < 0.001), whereas VFA obese group had longer insufflation time (165 vs. 182 min, p = 0.028), greater estimated blood loss (34 vs. 88 ml, p = 0.003) and greater specimen weight (255 vs. 437 g, p < 0.001) than VFA normal group. In a logistic regression analysis, high VFA value was a significant predictor for greater specimen weight and high VFA value and large size of renal tumor were significant predictors for greater blood loss. By contrast, BMI was not a significant predictor. Furthermore, in the case of non-obese patients (BMI < 25), VFA obese group had significantly longer insufflation time, greater estimated blood loss and greater specimen weight than normal group. Conclusions: The present data suggest that VFA is a more useful parameter than BMI for predicting the operative difficulty associated with obesity, and VFA has a higher use value in non-obese patients (BMI < 25) than in obese patients (BMI ≥ 25).