Inverse and nonlinear association between hemoglobin-to-red blood cell distribution width ratio and heart failure: evidence from NHANES 2011–2018

Background Heart failure (HF) is a growing global health concern associated with significant morbidity and mortality. The hemoglobin-to-red blood cell distribution width ratio (HRR) has emerged as a novel inflammatory biomarker that integrates information on anemia and red blood cell heterogeneity. However, the association between HRR and HF has not been thoroughly investigated in large population-based samples. Methods We analyzed data from 15,122 participants in the National Health and Nutrition Examination Survey (NHANES) 2011–2018. HRR was calculated as the ratio of hemoglobin (g/dL) to red blood cell distribution width (RDW, %). HF status was determined based on self-reported physician diagnosis. Weighted univariate and multivariable logistic regression models were used to assess the association between HRR and HF prevalence. Restricted cubic spline (RCS) and generalized additive models (GAM) were employed to explore non-linear relationships. Subgroup and interaction analyses were conducted to evaluate effect modifications across demographic and clinical strata. Results Participants with lower HRR were older, had higher prevalence of comorbidities, and worse cardiometabolic profiles. In unadjusted analyses, HRR was strongly inversely associated with HF (OR: 0.03; 95% CI: 0.02–0.05; p < 0.001). This relationship remained significant in fully adjusted models (OR: 0.08; 95% CI: 0.03–0.22; p < 0.001). Participants in the highest HRR tertile had 56% lower odds of HF compared to those in the lowest tertile (p for trend < 0.001). RCS analysis demonstrated a nonlinear inverse association between HRR and HF risk (p for non-linearity < 0.001). The association was robust across all subgroups, with no significant interactions observed. Conclusion Higher HRR is independently and non-linearly associated with a lower prevalence of HF in a nationally representative U.S. population. As an inexpensive and widely available hematologic parameter, HRR may serve as a practical biomarker for HF risk stratification. Further prospective studies are needed to validate its prognostic value and explore clinical applications in HF screening and management.