Usefulness of hypochloremia at the time of discharge to predict prognosis in patients with chronic heart failure after hospitalization

Background: Hypochloremia has been suggested as a strong marker of mortality in hospitalized patients with heart failure (HF). This study aimed to clarify whether incorporating hypochloremia into pre-existing prognostic models improved the performance of the models. Methods: We tested the prognostic value of hypochloremia (<97 mEq/L) measured at discharge in hospitalized patients with HF registered in the REALITY-AHF and NARA-HF studies. The primary outcome was 1-year mortality after discharge. Results: Among 2496 patients with HF, 316 (12.6 %) had hypochloremia at the time of discharge, and 387 (15.5 %) deaths were observed within 1 year of discharge. The presence of hypochloremia was strongly associated with higher 1-year mortality compared to those without hypochloremia (log-rank: p < 0.001), and this association remained even after adjustment for the Get With the Guideline–HF risk model (GWTG-HF), anemia, New York Heart Association (NYHA) classification, and log-brain natriuretic peptide (BNP) [hazard ratio (HR) 1.64; p < 0.001]. Furthermore, adding hypochloremia to the prediction model composed of GWTG-HF + anemia + NYHA class + log-BNP yielded a numerically larger area under the curve (0.740 vs 0.749; p = 0.059) and significant improvement in net reclassification (0.159, p = 0.010). Conclusions: Incorporating the presence of hypochloremia at discharge into pre-existing risk prediction models provides incremental prognostic information for hospitalized patients with HF.