ACS 2019: Variation in Estimated GFR Values Prior to Nephrectomy Based on Cystatin C, CKD-EPI, Cockcroft-Gault, and MDRD Formulas

San Francisco, California ( Gordon Hong discussed how pre-operative estimated Glomerular Filtration Rate (eGFR) is used to help counsel patients prior to nephrectomy on post-operative risk of renal function decline and to help guide treatment decisions. They compared four eGFR equations - Cystatin-C based Hoek formula (Cys-C), Modification of Diet in Renal Disease (MDRD), Cockcroft-Gault (C-G), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) - in the pre-operative setting to better understand the differences between these estimates and how they may affect clinical decision making.  Baseline demographics, comorbidities, and lab values were prospectively obtained on patients being considered for nephrectomy. Descriptive statistical analysis was performed, as was the calculation of the Pearson correlation coefficient (PCC) for each eGFR.

Fifty-eight patients were enrolled: 67% male, mean age 62 ± 11 years, BMI 31± 8.2, and 22% were African American. eGFR values varied greatly: 34% of patients had values that ranged > 30 points. eGFR range was lowest for CKD-EPI (28-114) and highest for C-G (27-169). Patients with a eGFR < 60 ranged from 19% according to Cys-C to 33% according to C-G. PCC ranged from 0.47 (Cys-C + C-G) to 0.98 (CKD-EPI + MDRD). Variation positively correlated with eGFR mean (r = 0.53). They concluded eGFR values can widely vary for a single patient depending on the utilized equation, with significant implications for surgical planning, candidacy for neoadjuvant trials, and adjuvant treatments after nephrectomy. Current research is underway evaluating the impact of such variation on outcomes after extirpative renal surgery. 

Presented by: Gordon Hong, BS, Emory University School of Medicine, Atlanta, Georgia, Emory University School of Medicine, Decatur, Georgia

Written by: Stephen B. Williams, MD, Medical Director for High Value Care; Chief of Urology, Associate Professor, Director of Urologic Oncology, Director Urologic Research, The University of Texas Medical Branch at Galveston, TX at the 2019 American College of Surgeons Clinical Congress October 27-31, 2019  - San Francisco, CA