The impact of body mass index on surgical outcomes of robotic partial nephrectomy

Abstract

Study Type--Therapy (case series) Level of Evidence 4. "What's known on the subject?" and "What does the study add?" Obesity is associated with higher incidence of renal cell carcinoma. Laparoscopic and robotic partial nephrectomy (RPN) was shown to be technically feasible in the obese population. In the present study we evaluated the impact of obesity on outcome of RPN, in a large cohort of patients. In the present study, obese patients had a higher American Society of Anesthesiologists score and larger tumour size. We evaluated obesity as a categorical and a continuous variable, and we adjusted for confounding factors. We categorized obesity based according to the WHO classification of obesity. We described our technical modifications to overcome difficulties that can be encountered during the surgery. Obese patients had a higher estimated blood loss, but no difference in blood transfusion rate, operation duration or warm ischaemia time. • To assess the impact of body mass index (BMI) on the surgical outcomes of robotic partial nephrectomy (RPN). • Medical charts of 250 consecutive patients who underwent RPN at our institution between 2006 and 2010 were reviewed. • Patients were categorized based on their BMI into four groups per international classification of obesity into: normal (BMI < 25 kg/m(2)), overweight (25-29.9), obese (30-39.9) and morbidly obese (≥ 40). • Preoperative characteristics as well as perioperative and postoperative outcomes were analysed and compared between the groups. • Of the 250 patients, 43 (17.2% of the entire cohort) were non-obese, 104 (41.6%) were overweight, 75 (30%) were obese, and 28 (11.2%) were morbidly obese. • Groups were similar in terms of age, gender, history of previous surgery and nephrometry score (P = 0.5). • Patients with higher BMI had a higher American Society of Anesthesiologists (ASA) score (median 3 for obese and morbidly obese groups vs 2 for non-obese groups; P = 0.002) and tumour size (median 3.6, 2.9, 2.5 and 2.3 cm in those who were morbidly obese, obese, overweight and with normal BMI, respectively; P = 0.005). • Patients within the morbidly obese group had a higher estimated blood loss (median 250 mL) than other groups (median: 200, 200, 150 mL, respectively) (P = 0.03). • No significant difference was detected between the groups in terms of operation duration, warm ischaemia time, transfusion rate and postoperative complications. • Robotic partial nephrectomy represents an effective treatment modality for renal tumours providing equivalent surgical outcomes even for patients with BMI up to 60 kg/m(2).