Renal function in heart failure: a disparity between estimating function and predicting mortality risk

Aims To compare the predictive value of estimated renal function calculated by the Chronic Kidney Disease Epidemiology Collaboration (eGFR CKD‐EPI ), four‐variable Modification of Diet in Renal Disease (eGFR MDRD‐4 ), and Cockcroft–Gault [estimated creatinine clearance (eCcr)] equation in terms of all‐cause mortality in heart failure. Renal function is an important prognostic factor in heart failure. Established methods of estimating renal function are known to under‐/overestimate true function in certain settings. Methods and results A total of 800 systolic heart failure outpatients (mean age 57 ± 11.5 years, 82% male) were studied over a median follow‐up of 121 (Q1–Q3: 110–130) months. The highest systematic difference was seen between eCcr and eGFR MDRD‐4 [+12.33 points (mean), 95% limits of agreement –22.35 to 47.01; generalized kappa = 0.36]. eGFR MDRD‐4 and eGFR CKD‐EPI were the most similar [–4.16 points (mean), 95% limits of agreement –11.56 to 3.25; generalized kappa = 0.74]. Up to 35.4% of patients were reclassified into different estimated glomerular filtration rate (eGFR) categories when comparing eGFR CKD‐EPI with eCcr and eGFR MDRD‐4 . eGFR CKD‐EPI performed marginally better in terms of predicting all‐cause mortality than eGFR MDRD‐4 , as univariate areas under the time‐dependent receiver operating characteristic curves (AUC), marginal and partial proportions of explained variation (PEV), net reclassification improvement (NRI), and the integrated discrimination improvement (IDI) for 5 years of follow‐up were significantly higher for eGFR CKD‐EPI than for eGFR MDRD‐4 . Conclusion In this cohort of heart failure patients, eGFR CKD‐EPI was marginally better in predicting all‐cause mortality than eGFR MDRD‐4 . Estimated function differed widely between equations and is likely to have an effect on therapy choice.