DECLININING BASELINE GFR IMPACTS SURVIVAL IN PATIENTS UNDERGOING PARTIAL OR RADICAL NEPHRECTOMY FOR RENAL CORTICAL TUMORS

Background—We evaluated the impact of baseline renal function and comorbidity index on survival in patients with renal tumors. Methods—We identified 1479 patients who underwent partial or radical nephrectomy between 1995 and 2005 for localized renal tumors. Demographic, clinicopathologic, body mass index (BMI) and comorbidity data (assessed by Charlson-Romano index and hypertension) were retrieved. We used the abbreviated modified diet and renal disease (MDRD) equation to estimate glomerular filtration rate (GFR) using the last preoperative serum creatinine. BMI and GFR time trends were analyzed with linear regression. The impact of BMI, comorbidity, and baseline GFR on disease-free and overall survival was studied using Cox regression controlling for pathologic stage, node and metastatic status. Results—Over a 10 year interval, median BMI increased from 27 (Interquartile Range [IQR]: 24,31) to 28 (IQR: 25,31, p=0.004), and median baseline GFR fell from 70 (IQR:58,80) to 63cc/min/ 1.73m2 (IQR: 57,78, p<0.001). Multivariable regression demonstrated an association between year of surgery and baseline GFR (p<0.001) even after adjusting for age, sex, comorbidity, BMI, and tumor size. We repeated the analysis for patients aged 18–70, and this association persisted (p<0.001). Baseline GFR, BMI, and comorbidity were not associated with disease-free-survival after controlling for stage. However, moderately reduced baseline GFR (45–60cc/min/1.73m2) and severely reduced GFR (<45cc/min/1.73m2) were significantly associated with overall survival (hazard ratio [HR] 1.5, p<0.003 and 2.8, p<0.001, respectively). Conclusions—There has been a time-dependent decline in baseline GFR over the last decade. Baseline GFR is an important preoperative consideration independently affecting overall survival.