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

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.

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).

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.