Prospective randomised non-inferiority trial of pelvic drain placement vs no pelvic drain placement after robot-assisted radical prostatectomy

Objectives To determine if eliminating the prophylactic placement of a pelvic drain (PD) after robot-assisted radical prostatectomy (RARP) affects the incidence of early (90-day) postoperative adverse events. Materials and Methods In this parallel-group, blinded, non-inferiority trial, we randomized patients planning to undergo RARP to one of two arms: no drain placement (ND) or PD placement. Patients with demonstrable intra-operative leakage upon bladder irrigation were excluded. Randomization sequence was determined a-priori using a computer algorithm, and included a stratified design with respect to low vs. intermediate/high D'Amico risk classifications. Surgeons remained blinded to the randomization arm until final eligibility was verified at the end of the RARP. The primary endpoint was overall incidence of 90-day complications which, based on our standard treatment using PD retrospectively, was estimated at 13%. The non-inferiority margin was set at 10%, and the planned sample size was 312. An interim analysis was planned and conducted when 1/3 of the planned accrual and follow-up was completed, to rule out futility if the delta margin was in excess of 0.1389. Results From 2012 to 2016, 189 patients were accrued to the study, with 92 patients allocated to the ND group and 97 patients allocated to the PD group. Due to lower than expected accrual rates, accrual to the study was halted by regulatory entities, and we did not reach the intended accrual goal. ND and PD groups were comparable in median PSA (6.3 vs 5.8 respectively, p=0.5), clinical stage (p=0.8), D'Amico risk classification (p=0.4), median lymph nodes dissected (17 vs 18, p=0.2) and proportion of patients receiving an extended pelvic lymph node dissection (70.7% vs 79.4% respectively, p=0.3). Incidence of 90-day overall and major (Clavien ≥ III) complications in the ND group (17.4% and 5.4%, respectively) was not inferior to the PD group (26.8% and 5.2%, respectively; p=0.0008 and p=0.007 for difference of proportions