Severity of Preoperative Proteinuria is a Risk Factor for Overall Mortality in Patients Undergoing Nephrectomy

Abstract

Chronic kidney disease may adversely affect survival following nephrectomy. Proteinuria is increasingly used as a marker of kidney disease. However, the relationship between preoperative proteinuria and survival after nephrectomy remains incompletely characterized. We evaluated the association of preoperative proteinuria with overall and cancer specific survival using our institutional nephrectomy registry. We identified 1,846 patients with localized clear cell renal cell carcinoma treated with curative intent (radical or partial nephrectomy) between 1995 and 2010. Patients were categorized for analysis based on preoperative proteinuria severity (mild, moderate or severe). Overall and cancer specific survival was estimated by the Kaplan-Meier method. Cox proportional hazards regression models were used to assess for variables associated with overall and cancer specific mortality. Preoperative urine protein testing was available in 1,347 patients (73%). A total of 804 patients (60%) were classified with mild proteinuria (less than 150 mg per day), 332 (25%) were classified with moderate proteinuria (150 to 500 mg per day) and 211 (16%) were classified with severe proteinuria (greater than 500 mg per day). On multivariable analysis with mild proteinuria as the reference category the adjusted HR for all cause mortality was 1.18 (95% CI 0.95-1.48, p=0.14) for moderate proteinuria and 1.61 (95% CI 1.26-2.07, p <0.001) for severe proteinuria. However, the proteinuria level was not associated with cancer specific survival. Severe preoperative proteinuria is associated with worse overall survival following radical or partial nephrectomy for localized clear cell renal cell carcinoma. Preoperative proteinuria should be evaluated in patients undergoing nephrectomy and considered when estimating overall patient health status.