Diabetes mellitus is the only independent predictor of both postoperative and long term renal functions in elective laparoscopic partial nephrectomy with limited or overextended warm ischemia

Objective: To investigate the predictive factors of renal functional change at postoperative period and at last follow-up in patients undergoing elective and clamped laparoscopic partial nephrectomy (LPN) with limited (≤20 minutes) and overextended (≥40 minutes) warm ischemia time (WIT). Material and methods: From our prospectively collected LPN database, elective and warm ischemia-applied LPNs were retrospectively analyzed in two groups: limited (n=55, Group 1, WIT≤20 minutes) and overextended (n=28, Group 2, WIT≥40 minutes) WITs. Preoperatively, estimated glomerular filtration rate (eGFR) was ≥60 mL/min/1.73 m² in all patients. Demographic, clinical, perioperative and renal functional parameters were compared between two groups. Age, diabetes mellitus (DM), pathological tumor size, preoperative eGFR and WIT were used in multivariable analyses to investigate the independent predictors of de novo Stage 3 or greater chronic kidney disease (CKD) (eGFR<60 mL/min/1.73m²) at postoperative period and at the last follow-up. Results: Preoperative (p=0.009) and pathological (p=0.011) tumor size, PADUA (p=0.001) and R.E.N.A.L. Nephrometry (p=0.006) scores and operative time (p<0.001) were significantly higher in Group 2. Preoperative eGFR (86 vs. 88 mL/min/1.73 m², p=0.328) was similar between two groups. In postoperative period, compared to Group 1, decreased eGFR (86 vs. 62.5 mL/min/1.73 m², p<0.001) and percent preserved eGFR (97.2 vs. 77.2%, p<0.001) were found in Group 2. After median follow-up of 33 and 30 months (p=0.732) for Groups 1 and 2, respectively, eGFR at the last follow-up (84 vs. 80.0 mL/min/1.73 m², p=0.347) and percentage preserved eGFR at last follow-up (97.7 vs. 92.5%, p=0.806) were similar between two groups. Overextended WIT (≥40 minutes), preoperative decreased eGFR (<77.5 mL/min/1.73m²) and DM were the independent predictors of de novo Stage 3 or greater CKD at postoperative period, while DM and age were the predictors of de novo Stage 3 or greater CKD at the last follow-up. Conclusion: Overextended WIT (≥40 minutes) caused significant postoperative renal functional loss in elective LPN but this functional loss recovers at long term follow-up. However, diabetes mellitus is the only predictor of renal functional loss both in the postoperative period and at the last follow-up.