Comparison of Cold and Warm Ischemia During Partial Nephrectomy in 660 Solitary Kidneys Reveals Predominant Role of Nonmodifiable Factors in Determining Ultimate Renal Function Brian R. Lane, Paul Russo, Robert G. Uzzo, Adrian V. Hernandez, Stephen A. Boorjian, R. Houston Thompson, Amr F. Fergany, Thomas E. Love and Steven C. Campbell*,† From the Glickman Urological & Kidney Institute (BRL, AFF, SCC), and Department of Quantitative Health Sciences (AVH), Cleveland Clinic, and Center for Health Care Research and Policy, Case Western Reserve University at MetroHealth Medical Center (TEL), Cleveland, Ohio, Division of Urology, Spectrum Health, Michigan State University, Grand Rapids, Michigan (BRL), Department of Urology, Memorial Sloan- Kettering Cancer Center, New York, New York (PR, RHT), Department of Urology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (RGU, SAB), and Department of Urology, Mayo Clinic, Rochester, Minnesota (SAB, RHT) Purpose: Factors that determine renal function after partial nephrectomy are not well- defined, including the impact of cold vs warm ischemia, and the relative importance of modifiable and nonmodifiable factors. We studied these determi- nants in a large cohort of patients with a solitary functioning kidney undergoing partial nephrectomy. Materials and Methods: From 1980 to 2009, 660 partial nephrectomies were performed at 4 centers for tumor in a solitary functioning kidney under cold (300) or warm (360) ischemia. Data were collected in institutional review board ap- proved registries and followup averaged 4.5 years. Preoperative and postopera- tive glomerular filtration rates were estimated via the Chronic Kidney Disease- Epidemiology Study equation. Results: At 3 months after partial nephrectomy median glomerular filtration rate 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 minutes respectively, p 0.001). On multivariable analyses increasing age, larger tumor size, lower preoperative glomerular filtration rate and longer isch- emia time were associated with decreased postoperative glomerular filtration rate (p 0.05). When percentage of parenchyma spared was incorporated into the analysis, this factor and preoperative glomerular filtration rate proved to be the primary determinants of ultimate renal function, and duration of ischemia lost statistical significance. Conclusions: This nonrandomized, comparative study suggests that within the relatively strict parameters of conventional practice, ie predominantly short ischemic intervals and liberal use of hypothermia, ischemia time was not an independent predictor of ultimate renal function after partial nephrectomy. Long-term renal function after partial nephrectomy is determined primarily by the quantity and quality of renal parenchyma preserved, although type and duration of ischemia remain the most important modifiable factors, and warrant further study. Key Words: carcinoma, renal cell; nephrectomy; ischemia Abbreviations and Acronyms AKI = acute kidney injury CI = cold ischemia CKD = chronic kidney disease eGFR = estimated glomerular filtration rate GFR = glomerular filtration rate PN = partial nephrectomy RCC = renal cell carcinoma sCr = serum creatinine level WI = warm ischemia Submitted for publication June 2, 2010. Study received institutional review board ap- proval. * Correspondence and requests for reprints: Glickman Urological & Kidney Institute, Cleveland Clinic, 9500 Euclid Ave., Q10, Cleveland, Ohio 44195 (telephone: 216-444-5595; FAX: 216-636- 0770; e-mail: campbes3@ccf.org). † Financial interest and/or other relationship with Pfizer and Sanofi-Aventis. See Editorial on page 383. 0022-5347/11/1852-0421/0 Vol. 185, 421-427, February 2011 THE JOURNAL OF UROLOGY ® Printed in U.S.A. © 2011 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RESEARCH,INC. DOI:10.1016/j.juro.2010.09.131 www.jurology.com 421