Obesity and 30-day Outcomes Following Minimally Invasive Nephrectomy.

OBJECTIVE: To evaluate the association between obesity and postoperative outcomes following minimally invasive partial nephrectomy (MIPN) and minimally invasive radical nephrectomy (MIRN).

METHODS: Using the National Surgical Quality Improvement Project database, we identified adult patients who underwent either MIPN or MIRN from 2012 to 2016. Patients were stratified by body mass index (BMI) according the World Health Organization classification of obesity (non-obese [BMI 18.5-29.9 kg/m2 ], class I obesity [BMI 30-34.9 kg/m2 ], class II obesity [BMI 35-39.9 kg/m2 ], and class III obesity [BMI≥40 kg/m2 ]). Multivariable logistic regressions alternately including obesity class, comorbidity score, and both were used to evaluate the association among these variables with post-operative outcomes.

RESULTS: A total of 21,334 patients (MIPN=10,444, MIRN=10,890) were included. When only obesity class or comorbidity score was included in our multivariable logistic regression model, both variables were associated with increased odds of overall 30-day complications. However, when both class or comorbidity were included in the model, comorbidity but not obesity was found to be associated with increased postoperative complications. Obesity was also not found to be associated with unplanned readmission. However, obesity was independently associated with prolonged operative time and discharge to continued care in the full model.

CONCLUSION: This NSQIP study suggests that BMI does not independently predict the likelihood of overall complications or readmission within 30 days, and should not be considered a major barrier for MIPN or MIRN. Instead, obesity should be taken into consideration with other comorbidities when risk-stratifying patients prior to minimally invasive nephrectomy.