Serum Albumin Modifies the Prognostic Meaning of BNP in Acute Decompensated Heart Failure

BNP is widely used for risk stratification in acute decompensated heart failure (ADHF), but its prognostic meaning may differ across clinical phenotypes, particularly cardiorenal syndrome type 1 (CRS1).

We hypothesized that serum albumin modifies the association between BNP and adverse in-hospital course in ADHF.

In this retrospective cohort study, adults hospitalized with ADHF were classified as CRS1 or control. The primary endpoint was adverse in-hospital course, defined as in-hospital death and/or prolonged length of stay (≥ 75th percentile). BNP was analyzed on the natural log scale. Multivariable logistic regression included albumin, ln(BNP), and an albumin × ln(BNP) interaction term, adjusted for age, sex, systolic blood pressure, eGFR, ejection fraction, CRS status, body mass index, and diabetes mellitus.

In the complete-case cohort (N = 292; events = 77), albumin significantly modified the BNP-risk association (interaction β = -0.236 per 5 g/L; Wald p = 0.045; likelihood-ratio test p = 0.050). The adjusted odds ratio for a 1-unit increase in ln(BNP) was 1.81 at albumin 30 g/L, 1.42 at 35 g/L, and 1.12 at 40 g/L. Discrimination improved modestly with the interaction (AUC 0.714 vs. 0.726), and the high-BNP/low-albumin stratum showed the highest observed event risk.

Serum albumin modifies the prognostic meaning of BNP in ADHF. Integrating albumin into BNP interpretation identifies a high-risk "congestion plus vulnerability" phenotype and may support pragmatic triage and discharge planning in CRS-enriched ADHF populations.