BACKGROUND

Correct estimation of renal function is crucial in assessing prognosis of patients with heart failure (HF). Recently, two new equations have been proposed to calculate estimated glomerular filtration rate (eGFR) with cystatin C alone or both creatinine and cystatin C. We assessed the prognostic value of eGFR estimated by these new equations in outpatients with HF.

METHODS

The study included 879 patients with median age, 70.4 years; main etiology of HF ischemic heart disease, 52.7%; and median LVEF, 34%.

RESULTS

eGFR estimates by the new equations correlated significantly with eGFR estimates from previous equations, with the best correlation observed between the 2 equations containing cystatin C [intraclass correlation coefficient 0.95 (95% confidence interval 0.94-0.95)]. During a median follow-up of 3.94 years, 371 patients died. The Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equations containing cystatin C were found to be best for predicting death [area under the ROC curve 0.685 for CKD-EPI-cystatin C and 0.672 for CKD-EPI-creatinine-cystatin C vs 0.632 for simplified Modification of Diet in Renal Disease Study traceable to isotope dilution mass spectrometry and 0.643 for CKD-EPI (all P < 0.001)]. The CKD-EPI-cystatin C equations also showed significantly better calibration and reclassification measurements for both integrated discrimination improvement and net reclassification improvement in predicting death (P < 0.001). Reclassification with these new equations was particularly better in the subgroup with intermediate eGFR [45-74 mL · min(-1) · (1.73 m(2))(-1)].

CONCLUSIONS

The two new CKD-EPI equations containing cystatin C are useful for HF risk stratification and show better prognostic performance than creatinine-only based eGFR equations, mostly in patients with intermediate eGFR. These equations seem appropriate for assessing prognosis of HF patients with moderate renal insufficiency.