Associations Between Hemoglobin and Serum Iron Levels and the Risk of Mortality Among Patients with Coronary Artery Disease

Background: The relationship between hemoglobin and serum iron levels and mortality risk in patients with coronary artery disease (CAD) is not well understood. Methods: We analyzed data from 3,224 patients with CAD using Cox proportional hazards regression models to assess the association of hemoglobin and serum iron levels with cardiovascular and all-cause mortality. Results: Over a median follow-up period of 8.9 years, 636 patients died, including 403 from cardiovascular causes. Higher hemoglobin and serum iron levels were linked to a reduced risk of cardiovascular and all-cause mortality. Patients in the highest quartiles of hemoglobin and serum iron levels had multivariable-adjusted hazard ratios (HRs) of 0.62 (95% CI, 0.46–0.85) and 0.51 (95% CI, 0.37–0.69) for cardiovascular mortality, and 0.64 (95% CI, 0.50–0.83) and 0.67 (95% CI, 0.53–0.85) for all-cause mortality, compared to those in the lowest quartile. A one-standard deviation increase in hemoglobin and serum iron levels corresponded to a 19% and 24% reduction in cardiovascular mortality risk and a 19% reduction in all-cause mortality risk for both factors. Restricted cubic spline analysis revealed L-shaped and U-shaped associations between hemoglobin and serum iron levels and cardiovascular and all-cause mortality, respectively. These associations were consistent across various age groups, sex, and CAD types. Conclusions: Hemoglobin and serum iron levels are significantly associated with lower risks of cardiovascular and all-cause mortality in patients with CAD. Further research is needed to evaluate the effects of iron supplementation in these patients.