Warm ischemia time length during on-clamp partial nephrectomy: does it really matter?

Abstract

The impact of warm ischemia time (WIT) on renal functional recovery remains controversial. We examined the length of WIT>30 min on the long-term renal function following on-clamp partial nephrectomy (PN). Data from 23 centers for patients undergoing on-clamp PN between 2000 and 2018 were analyzed. We included patients with two kidneys, single tumor, cT1, minimum 1-year follow-up, and preoperative eGFR≥60 mL/min/1.73m2. Patients were divided into two groups according to WIT length: group I "WIT≤30 min" and group II "WIT>30 min." A propensity-score matched analysis (1:1 match) was performed to eliminate potential confounding factors between groups. We compared eGFR values, eGFR (%) preservation, eGFR decline, events of chronic kidney disease (CKD) upgrading, and CKD-free progression rates between both groups. Cox regression analysis evaluated WIT impact on upgrading of CKD stages. The primary cohort consisted of 3526 patients: group I (N.=2868) and group II (N.=658). After matching the final cohort consisted of 344 patients in each group. At last follow-up, there were no significant differences in median eGFR values at 1, 3, 5, and 10 years (P>0.05) between the matched groups. In addition, the median eGFR (%) preservation and absolute eGFR change were similar (89% in group I vs. 87% in group II, P=0.638) and (-10 in group I vs. -11 in group II, P=0.577), respectively. The 5 years new-onset CKD-free progression rates were comparable in the non-matched groups (79% in group I vs. 81% in group II, log-rank, P=0.763) and the matched groups (78.8% in group I vs. 76.3% in group II, log-rank, P=0.905). Univariable Cox regression analysis showed that WIT>30 min was not a predictor of overall CKD upgrading (HR:0.953, 95%CI 0.829-1.094, P=0.764) nor upgrading into CKD stage ≥III (HR:0.972, 95%CI 0.805-1.173, P=0.764). Retrospective design is a limitation of our study. Our analysis based on a large multicenter international cohort study suggests that WIT length during PN has no effect on the long-term renal function outcomes in patients having two kidneys and preoperative eGFR≥60 mL/min/1.73m2.