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

BaCKgroUnd: 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). MeThodS: 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. reSUlTS: 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. ConClUSionS: 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,