The impact of body mass index on perioperative outcomes in robot-assisted laparoscopic partial nephrectomy

Obese patients undergoing surgical procedures are at increased risk for perioperative morbidity. The purpose of this study is to determine whether there is an association with body mass index (BMI), clinicopathologic features, and perioperative outcomes and complications in patients undergoing robot-assisted laparoscopic partial nephrectomy (RPN).

Medical records of 283 patients who underwent RPN between 2007 and 2012 were reviewed from an Institutional Review Board approved database. We analyzed the association of perioperative outcomes and complications of the surgery with BMI and clinicopathologic features using analysis of variance, Kruskal-Wallis test, t test and chi-square-test. Eventually, independent factors associated with perioperative outcomes and complications were studied using univariate and multivariate regression analysis.

Perioperative outcomes including estimated blood loss (EBL), length of hospital stay (LOS) and operative time (OT) were significantly associated with BMI (P=0.002, P=0.009 and P=0.002, respectively). Warm ischemia time (WIT), perioperative complications, and change in glomerular filtration rate (GFR) before and after surgery were not associated with BMI (P=0.459, P=0.86 and P=0.773). In multivariate analysis, BMI, tumor size≥4 cm, and collecting system invasion were independently associated with EBL and OT. Increased LOS was independently associated with BMI and tumor size ≥4 cm.

Increasing BMI was not associated with a significant increase in perioperative complications, WIT, or change in GFR in patients undergoing RPN at a high-volume tertiary medical center. Collecting system invasion or tumor size ≥4 cm and BMI were independently associated with higher EBL, LOS, and OT, however.