Determinants of renal functional decline after open partial nephrectomy: A comparison of warm, cold, and non-ischemic modalities

Introduction: Renal functional decline after partial nephrectomy (PN) may be related to a variety of nonmodifiable and modifiable factors, including ischemia time (IT) and modality. We sought to determine the impact of these factors on renal functional degeneration after PN. Materials and methods: Multicenter retrospective analysis (n = 347) was performed, identifying patients who underwent open PN using warm, cold, and non- ischemic techniques. Primary outcome was development of de novo chronic kidney disease (CKD), (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m²), at 1 year follow up. Univariate and multivariable analysis (MVA) were performed examining factors associated with ischemia technique and the development of de novo CKD. Results: Median follow up 34.7 months. Two hundred and forty-one patients underwent warm ischemic, 31 cold ischemic, and 75 clampless PN. Patient characteristics were similar between groups. Clampless group had lower mean RENAL scores (6.4) than cold (7.9, p = 0.005) and warm (7, p = 0.037) ischemia groups. Cold ischemia cohort had longer median IT than the warm cohort (50min versus 25 min, p = 0.001). There were no significant differences in proportion of patients developing de novo CKD (warm 14.9%, cold 15%, clampless 8.7%, p = 0.422). MVA demonstrated that neither ischemic modality nor IT ≥ 30 minutes was associated with development of de novo CKD, while RENAL scores of increasing complexity (RENAL score 7-9 OR 4.32, p = 0.003; RENAL score ≥ 10 OR 15.42, p < 0.001) were independently associated with de novo CKD. Conclusions: Increasing tumor complexity, as indicated by the RENAL score, was an overriding determinant of post PN renal functional outcome. Prospective investigation is requisite to elucidate risk and protective factors for renal functional degeneration after PN.