External validation of yonsei nomogram predicting chronic kidney disease development after partial nephrectomy: An international, multicenter study.

OBJECTIVE: To externally validate Yonsei nomogram. METHODS: From 2000 through 2018, 3526 consecutive patients underwent on-clamp PN for cT1 renal masses at 23 centers were included. All patients had two kidneys, preoperative eGFR ≥60 ml/min/1.73 m2, and a minimum follow-up of 12 months. New-onset CKD was defined as upgrading from CKD stage I or II into CKD stage ≥III. We obtained the CKD-free progression probabilities at 1, 3, 5, and 10 years for all patients by applying the nomogram found at https://eservices.ksmc.med.sa/ckd/. Thereafter, external validation of Yonsei nomogram for estimating new-onset CKD stage ≥III was assessed by calibration and discrimination analysis. RESULTS AND LIMITATION: Median values of patients' age, tumor size, eGFR and follow-up period were 47 years (IQR: 47-62), 3.3 cm (IQR: 2.5-4.2), 90.5 ml/min/1.73 m2 (IQR: 82.8-98), and 47 months (IQR: 27-65), respectively. A total of 683 patients (19.4%) developed new-onset CKD. The 5-year CKD-free progression rate was 77.9%. Yonsei nomogram demonstrated an AUC of 0.69, 0.72, 0.77, and 0.78 for the prediction of CKD stage ≥III at 1, 3, 5, and 10 years, respectively. The calibration plots at 1, 3, 5, and 10 years showed that the model was well calibrated with calibration slope values of 0.77, 0.83, 0.76, and 0.75, respectively. Retrospective database collection is a limitation of our study. CONCLUSIONS: The largest external validation of Yonsei nomogram showed good calibration properties. The nomogram can provide an accurate estimate of the individual risk of CKD-free progression on long-term follow-up.

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.