Off-Clamp Versus On-Clamp Robot-Assisted Partial Nephrectomy: A Meta-Analysis of Clinical Trials and Matched Cohort Studies

Kidney cancer incidence continues to rise globally, with partial nephrectomy established as the standard of care for localized renal masses. Robot-assisted partial nephrectomy has become the preferred approach, with debate continuing regarding the optimal management of renal blood flow during tumor excision. While on-clamp techniques involve temporary renal artery occlusion to minimize blood loss, off-clamp approaches avoid ischemic injury by maintaining continuous renal perfusion. This meta-analysis aimed to compare perioperative, functional, and oncological outcomes between off-clamp and on-clamp robot-assisted partial nephrectomy. A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, searching PubMed, Web of Science, Scopus, and Cochrane databases. Twenty studies, comprising two randomized controlled trials and 18 observational studies, were included, totaling 4,961 patients after matching. Quality assessment utilized the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias 2 tool for randomized trials. Meta-analysis employed risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous variables, with random-effects models applied when heterogeneity exceeded 50%. Publication bias was assessed using funnel plots and Egger's regression test. Off-clamp robot-assisted partial nephrectomy demonstrated significantly lower major complication rates compared to on-clamp techniques (RR: 1.66, p = 0.018). Renal function preservation favored the off-clamp approach, with better postoperative glomerular filtration rate (MD: -3.45 mL/min/1.73 m², p < 0.0001). The on-clamp technique showed less estimated blood loss (MD: -32.7 mL, p < 0.0001), though this did not translate to differences in transfusion requirements (RR: 0.80, p = 0.208). Operative time was longer for off-clamp procedures (MD: 21.55 minutes, p = 0.030). Hospital stay duration did not differ significantly between techniques (MD: 0.02 days, p = 0.946). Subgroup analysis by follow-up duration revealed that renal function benefits were most pronounced at intermediate (three to nine months) and long-term (≥12 months) follow-up. Our study concluded that off-clamp robot-assisted partial nephrectomy offers superior safety, with significantly reduced major complications and better preservation of renal function, particularly at intermediate and long-term follow-up, despite requiring longer operative time. Both techniques demonstrate equivalent oncological efficacy with comparable positive surgical margins. The off-clamp approach should be preferred for patients at high risk of ischemic injury. At the same time, technique selection should be individualized based on patient renal reserve, tumor complexity, and surgical expertise.