Campbell, Steven C.

321 Background: Factors that determine renal function after partial nephrectomy (PN) are not well defined, including the impact of cold vs. warm ischemia and the relative importance of modifiable and non-modifiable factors. We studied these determinants in a large cohort of patients with a solitary functioning kidney undergoing PN. Methods: In 1980–2009, 660 PN were performed at 4 centers for tumor in a solitary-functioning kidney under cold (n=300) or warm (n=360) ischemia. Data were collected in IRB-approved registries; follow- up averaged 4.5 years. Pre- and postoperative glomerular filtration rates (GFR) were estimated via CKD-EPI equation. Results: At 3 months after PN, median GFR decreased by equivalent amounts with cold or warm ischemia (21% vs. 22%, respectively, p=0.7) although median cold ischemic times were much longer (45 vs. 22 min. respectively, p<0.001). In multivariable analyses, increasing age, larger tumor size, lower preoperative GFR, and longer ischemia time were associated with decreased postoperative GFR (p<0.05). When percentage of parenchyma spared was incorporated into the analysis, this factor and preoperative GFR proved to be the primary determinants of ultimate renal function, and duration of ischemia lost statistical significance. Conclusions: This non-randomized comparative study suggests that long-term renal function after PN is determined primarily by the quantity and quality of renal parenchyma that can be preserved. Within the relatively strict parameters of conventional practice, i.e. predominantly short ischemic intervals and liberal use of hypothermia, ischemia time was not an independent predictor of ultimate renal function after PN. Nevertheless, type and duration of ischemia remain the most important modifiable factors during PN, and mandate further study. [Table: see text]