Estimated GFR and Mortality in Older Men: Are All eGFR Formulae Equal?

Background: Recently, the first estimated glonnerular filtration rate (eGFR) formula specifically developed for community -dwelling older adults, the Berlin Initiative Study Equation 2 (BIS2), was reported. To date, however, no study has examined the performance of the BIS2 to predict death in older adults as compared to equations used clinically and in research. Methods: We prospectively followed 2,994 community -dwelling men (age 76.4 +/- 5.6) enrolled in the MrOS Sleep Study. We calculated baseline eGFR from serum creatinine and cystatin-C using the BIS2, Chronic Kidney Disease Epidemiology (CKD-EPIcr,cy), CKD-EPIcy and CKD-EPI equations. Analyses included Cox-proportional hazards regression and net reclassification improvement (NRI) for the outcomes of all -cause and cardiovascular death. Results: Follow-up time was 7.3 +/- 1.9 years. By BIS2, 42 and 11% had eGFR <60 and <45, respectively, compared to CKD-EPI (23 and 6%), CKD-EPIcysc (36 and 13%) and CKD-EPIcr.cysc (28 and 8%). BIS2 eGFR <45 was associated with twofold higher rate of all -cause mortality when compared to eGFR 75 after multivariate adjustment (HR 2.1, 95% CI 1.5-2.8). Results were similar for CKD-EPIcr,cysc <45 (HR 2.1, 95% CI 1.6-2.7) and CKDEPIcy <45 (HR 2.1, 95% CI 1.7-2.7) and weaker for CKD-EPI <45 (HR 1.5, 95% C11.2-2.0). In NRI analyses, when compared to CKD-EPIcr,cyso both BIS2 and CKD-EPIcr equations more often nnisclassified participants with respect to mortality. We found similar results for cardiovascular death. Conclusion: The BIS2 did not outperform and the CKD-EPI was inferior to the cystatin C-based CKD-EPI equations to predict death in this cohort of older men. Thus, the cystatin C-based CKDEPI equations are the formulae of choice to predict death in community-dwelling older men. (C) 2016 S. Karger AG, Basel