Randomized Clinical Trial Comparing On-clamp Versus Off-clamp Laparoscopic Partial Nephrectomy for Small Renal Masses (CLOCK II Laparoscopic Study): A Intention-to-treat Analysis of Perioperative Outcomes

In the setting of a randomized controlled trial, no differences were found in the perioperative and early functional outcomes between on- and off-clamp laparoscopic partial nephrectomy. Recent randomized trials (RCTs) in the field of robotic partial nephrectomy (PN) showed no significant differences in perioperative outcomes between the off- and on-clamp approaches. To compare the perioperative outcomes of on- versus off-clamp pure laparoscopic PN (LPN). A multi-institutional analysis of the on- versus off-clamp approach during LPN in the setting of an RCT (CLOCK II trial; ClinicalTrials.gov NCT02287987) was performed. Off- versus on-clamp LPN. Baseline patient and tumor variables, and peri- and postoperative data were collected. Randomized allocation with a 1:1 ratio was assigned. Surgical strategy for managing the renal pedicle was dictated by the study protocol. In the off-clamp arm, the renal artery had to remain unclamped for the duration of the whole procedure. Reporting the intention-to-treat analysis is the purpose of the study. The study recruited 249 patients. Of them, 123 and 126 were randomized and allocated into the on- and off-clamp treatment groups, respectively. Treatment groups were comparable at baseline after randomization with respect to patients’ demographics, comorbidities, renal function, and tumor size and complexity. A univariable analysis found no differences in the perioperative outcomes between the groups, including median (interquartile range) estimated blood loss (150 [100–200] vs 150 [100–250] ml, p = 0.2), grade ≥2 complication rate as classified according to the Clavien-Dindo system (5.7% vs 4.8%, p = 0.6), and positive surgical margin rate (8.2% vs 3.5% for the on- vs off-clamp group, p = 0.1). No differences were found in terms of the 1st (81.3 [66.7–94.3] vs 85.3 [71.0–97.7] ml/min, p = 0.2) and 5th postoperative days estimated glomerular filtration rate (83.3 [70.5–93.7] vs 83.4 [68.6–139.3] ml/min, p = 0.2). A multivariable analysis found each +1 increase in RENAL score corresponded to an increase in the protection from the occurrence of complications (odds ratio [OR] 0.72, 95% confidence interval [CI] 0.54–0.97, p = 0.034), while each +1 cm increase in tumor size corresponded to an increase in the risk of blood transfusion (OR 1.39, 95% CI 1.14–1.70, p = 0.001). In the setting of an RCT, no differences were found in the perioperative and early functional outcomes between on- and off-clamp LPN. In this study, we invest