Estimated glomerular filtration rate and prognosis in heart failure: value of the Modification of Diet in Renal Disease Study-4, chronic kidney disease epidemiology collaboration, and cockroft-gault formulas.

OBJECTIVES The purpose of this study was to assess the value of estimated glomerular filtration rate (eGFR) calculated by different formulas for predicting the risk of death in heart failure (HF) outpatients. BACKGROUND Patients with both HF and renal insufficiency have a poor prognosis. Three formulas are mostly used to assess renal function: Cockroft-Gault formula, MDRD-4 (Modification of Diet in Renal Disease Study) formula, and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The prognostic values of these formulas have not been adequately compared in HF patients. METHODS A total of 925 patients (72% men; age 69 years; interquartile range: 59 to 75.5 years) with a left ventricular ejection fraction of 31% (interquartile range: 23.5% to 39%) were studied. Follow-up was 1,202 days (interquartile range: 627.5 to 2,156.5 days). Measures of performance were evaluated using continuous data and by dividing patients into 4 subgroups according to the eGFR: ≥90, 89 to 60, <60 to 30, and <30 ml/min/1.73 m(2). RESULTS The 3 formulas correlated significantly, with the best correlation found between the MDRD-4 and CKD-EPI formulas. The 3 formulas afforded independent prognostic information over long-term follow-up. However, risk prediction was most accurate using the Cockroft-Gault formula as evaluated by Cox proportional hazards models (hazard ratio: 0.75 vs. 0.81 with the MDRD-4 formula and 0.80 with the CKD-EPI equation), area under the curve (0.67 vs. 0.62 and 0.64, respectively), and Bayesian information criterion (both analyzing eGFR as a continuous or categorical variable). Indeed, net reclassification improvement and integrated discrimination improvement using the Cockroft-Gault formula were 21% and 5.04, respectively, versus the MDRD-4 formula (the most used) and 13.1% and 3.77 respectively versus CKD-EPI equation (the more recent) (all p values <0.001). CONCLUSIONS In this ambulatory, real-life cohort of HF patients, the Cockroft-Gault formula was the most accurate of the 3 used eGFR formulas to improve the risk stratification for death.