Off-clamp Versus On-clamp Robotic Partial Nephrectomy: A Systematic Review and Meta-Analysis

Objective: Off-clamp robot-assisted partial nephrectomy (RAPN) has been described as an alternative to on-clamp RAPN with the aim of eliminating warm ischemia time. As surgical decisions are largely affected by tumor complexity and size, adjustment for selection bias and confounders is desirable. We aimed to compare intraoperative and postoperative outcomes between off-clamp and on-clamp RAPN, using data from randomized controlled trials (RCTs) or covariate-matched studies (propensity-score matched or matched pair analysis). Methods: A PRISMA-compliant literature review was conducted on PubMed, EMBASE, Scopus and CENTRAL for relevant studies comparing off-clamp to on-clamp RAPN. Primary outcomes were estimated blood loss, postoperative percentage decrease in eGFR, and margin positive rate. Secondary outcomes were operative time, postoperative eGFR, length of stay, all postoperative complications, major complications, and need for transfusion. Random-effects meta-analyses were performed to generate mean differences (MD) or odds ratios (OR). Results: Ten studies (2307 patients) were shortlisted for analysis. There was no significant difference in estimated operative blood loss between off-clamp and on-clamp RAPN (MD 21.9 ml, 95%CI -0.9-44.7 ml, p=0.06, I2 =58%). Off-clamp RAPN yielded a smaller postoperative eGFR deterioration (MD 3.10%, 95%CI 1.05-5.16%, p=0.008, I2 =13%) and lower odds of margin positivity (OR 0.62, 95%CI 0.40-0.94, p=0.03, I2 =0%). No significant differences were found for all secondary outcomes. Conclusions: Off-clamp and on-clamp RAPN are similarly effective approaches for selected renal masses. Within the classic trifecta of partial nephrectomy outcomes, off-clamp RAPN yields similar rates of perioperative complications and may possibly offer better preservation of renal function and reduced margin-positive rates.