Prognostic value of formulas estimating excretory renal function in the elderly with systolic heart failure

Background: reduced renal excretory function (REF) is increasingly being appreciated as a potent prognostic factor in chronic heart failure (CHF). The Cockroft-Gault (CG) and the simplified Modification of Diet in Renal Disease (MDRD) equations have been recommended to estimate REF. However, limitations for both formulas have been reported in the elderly. Their prognostic performance in older CHF patients has not been investigated. Objectives: to assess the factors independently associated with all-cause mortality and compare the prognostic value of formulas estimating REF in CHF patients aged >= 70 years. Design: a longitudinal study with a median follow-up of 859 days. The end-point was all-cause mortality. Setting: Division of Cardiology and Cardiac Rehabilitation. Subjects: two hundred and sixty-six patients aged >= 70 years with systolic CHF. Methods: REF was estimated using the CG (eCrCl(CG)) and the MDRD (eGFR(MDRD)) formulas. Cox proportional hazards model was used to assess the factors independently associated with mortality and compare the prognostic value of estimating formulas. Receiver-operating characteristic (ROC) curve analysis was also performed. Results: Kaplan-Meier estimates of the rates of death at 1 and 2 years were 85% and 73%, respectively At multivariate analysis, eCrCl(CG) < 50 mL/min (P = 0.005), anaemia (P = 0.012), non-prescription of beta-blockers (P = 0.006) and left ventricular ejection fraction (P = 0.03) were the only independent predictors of mortality. On ROC analysis, the eCrCl(CG) was significantly more accurate than the eGFR(MDRD). Conclusions: among CHF patients aged >= 70 years, reduced REF is the most powerful independent predictor of survival. The excess in risk conferred by reduced REF is better appraised by means of the CG than the MDRD equation.