The CALLY Index as an integrated inflammation–nutrition biomarker for risk stratification in HFpEF

Background Heart failure with preserved ejection fraction (HFpEF) is a complex systemic syndrome characterized by inflammation, metabolic dysregulation, and immune imbalance. However, simple and integrative biomarkers for risk stratification remain limited. The C-reactive protein–albumin–lymphocyte (CALLY) index, reflecting inflammation, nutritional status, and immune function, has shown prognostic value in various diseases, but its role in HFpEF remains unclear. Methods In this single-center retrospective cohort study, 308 patients with HFpEF were enrolled. The CALLY index was calculated as albumin × lymphocyte count / CRP. The primary endpoint was major adverse cardiovascular events (MACE), defined as all-cause death or heart failure rehospitalization. Cox proportional hazards models, restricted cubic spline (RCS), receiver operating characteristic (ROC) analysis, and Kaplan–Meier curves were applied. Results During follow-up, 87 patients (28.25%) experienced MACE. Multivariable Cox analysis identified the CALLY index (HR = 0.98, 95% CI: 0.96–0.99) and E/e′ (HR = 1.08, 95% CI: 1.01–1.17) as independent predictors of MACE. RCS analysis demonstrated a nonlinear inverse association between the CALLY index and MACE risk. ROC analysis showed good predictive performance (AUC = 0.82). Patients with lower CALLY index (< 11.8) had significantly higher event rates (log-rank p < 0.001). Conclusions The CALLY index is an independent predictor of long-term outcomes in HFpEF, integrating inflammation, nutrition, and immune status. It may serve as a simple and practical tool for risk stratification.