Renal biomarkers and outcomes in outpatients with heart failure: The Atlanta cardiomyopathy consortium

Background/objectives Cystatin-C and beta-2-microglobulin may be superior to serum creatinine, blood urea nitrogen (BUN), or estimated glomerular filtration rate (EGFR) in patients hospitalized with heart failure (HF). We compared these renal markers in ambulatory HF patients. Methods We prospectively evaluated the association of baseline renal markers and EGFR (by 4 different formulas) with (1) the composite of death or HF-related hospitalization and (2) rates of hospitalizations and emergency department (ED) visits in 166 outpatients with HF (57.3 ± 11.6 years; 57.2% white, 38.6% black, median left ventricular ejection fraction 27.5% [17.5, 40.0]). Results After a median of 3.9 years, 63 (38.0%) patients met the composite endpoint. There were 458 hospitalizations (177 [38.6%] for HF) and 209 ED visits (51 [24.4%] for HF). Cystatin-based EGFR most consistently predicted (1) the composite endpoint (highest-to-lowest tertile adjusted hazard ratio [HR] 4.92 [95% CI 2.07-11.7; P < 0.001]); and (2) hospitalization rates, including HF hospitalizations (highest-to-lowest tertile, adjusted relative rate 5.24 [95% CI 1.61-17.01; P = 0.006]). Serum creatinine alone was a strong predictor of the composite endpoint (highest-to-lowest tertile, adjusted HR 3.20 [95% CI, 1.51-6.78; P = 0.002]). Only the highest tertile of BUN was associated with rates of ED visits. Conclusions In outpatients with HF, cystatin-based EGFR provides consistent prognostication across outcomes, except ED visits. Serum creatinine is an adequate prognosticator of death or HF hospitalization.