AUA 2018: Preoperative Kidney Function Trends: Improving estimates of Baseline Kidney Function prior to Kidney Cancer Surgery

San Francisco, CA ( Preoperative kidney function is strongly associated with significant postoperative chronic kidney disease (CKD) after kidney cancer surgery. Baseline kidney function is often estimated using a single preoperative measurement. The authors attempted to determine if preoperative kidney function trends were associated with the development of significant CKD in a national integrated health care system.  

Using the Veterans Health Administration database, the authors identified all patients who underwent radical or partial nephrectomy from 2004 to 2014. All patients with 5 or more preoperative kidney function measurements spanning two preoperative years and a preoperative estimated glomerular filtration rate (eGFR) > 30 mL/min/1.73 m2 were included in the analysis. Preoperative kidney function trends were calculated from a linear regression model using all eGFR values in the period of 24 months before nephrectomy. The primary outcome was time to eGFR < 30. The analysis was stratified by radical nephrectomy (n=6,443) or partial nephrectomy (n=3,279). Proportional hazard models controlling for clinical and tumor characteristics to preoperative kidney function trends were performed. 

In this cohort of 9,722 patients and 86,884 kidney function measurements, the median pre-operative eGFR was 67.8 (IQR 53.3 to 83.8). The mean slope of the preoperative eGFR was -2.5 mL/ min/1.73 m2 /year (SD 9.6) and varied by surgery type (-3.3 before radical; and -0.9 before partial). Patients with faster decline in preoperative kidney function were more likely to develop postoperative CKD (HR 1.02, 95%CI 1.015 to 1.022). In fully adjusted models, preoperative kidney function trends were associated with time to eGFR < 30 (HR 1.013, 95%CI 1.01 to 1.02) and overall survival (HR 0.995, 95%CI 0.991 to 0.998).  

The authors concluded that the preoperative trend in kidney function was independently associated with significant postoperative CKD following radical or partial nephrectomy, even after adjusting for preoperative baseline kidney function measurements. Preoperative kidney function trends can help identify subclinical CKD and patients at risk for poorer renal outcomes and survival. This has the potential to aid medical decision making and patient counseling. 

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Presented By: Andrew Sun, Standford, CA, USA 

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre Twitter: @GoldbergHanan at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA
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