Neutrophil-mean hemoglobin concentration ratio (NMHR) index and its association with heart failure morbidity and mortality

The purpose of this cross-sectional study was to investigate the relationship between the ratio of neutrophil count to mean hemoglobin concentration (NMHR) and the presence of heart failure (HF) and mortality. This study utilizing data from the National Health and Nutrition Examination Survey (NHANES) 2001–2018, with subsequent external validation performed through a hospital-based cohort. The logistic regression model and Cox proportional hazards model were used to analyze the association between the NMHR index and the prevalence of HF as well as the risk of all-cause mortality. Restricted cubic spline (RCS) analysis linear or nonlinear relationships between the NMHR index and HF or mortality were explored.The mediation analysis was conducted to examine the potential indirect effect of NMHR on all-cause mortality and cardiovascular mortality, mediated by HF. The study enrolled 75,274 participants from the NHANES database (n = 40,478) and the hospital validation cohort (n = 34,796), identifying 1,234 HF cases in the NHANES population and 7,479 HF cases in the hospital validation set. In the NHANES cohort, the NMHR index remained positively associated with the prevalence of HF, as shown by an OR of 1.57 (95% CI, 1.17–2.10; p < 0.05) when comparing Quartile 4 to Quartile 1. Similar results were consistently observed in the external hospital-based validation. For HF participants, with every unit increase in the NMHR index, there was an adjusted HR of 1.43 for all-cause mortality (95% CI: 1.17–1.75). and 1.31 (95% CI = 1.24–1.38) in those without HF. HF acted as a partial mediator in the association between NMHR and both all-cause and cardiovascular mortality, accounting for 3.1% and 4.1% of the total effect, respectively. In this cross-sectional analysis, the NMHR index was positively associated with a higher prevalence of HF. After adjusting for confounding factors, a higher NMHR index was significantly associated with increased all-cause and cardiovascular mortality.