Hemoglobin-to-Red Cell Distribution Width Ratio Was Associated with Cardiovascular Diseases and Death

Background/Objectives: The hemoglobin-to-red blood cell distribution width (RDW) ratio (HRR) reflects the status of inflammation and oxidative stress size. Previously, it has been suggested that HRR is associated with cardiovascular diseases (CVD). However, evidence has been limited for examining the association between HRR and the incidence of specific cardiovascular events (e.g., cardiovascular disease, stroke, congestive heart failure) and all-cause cardiovascular death and non-cardiovascular death, adjusting for known confounders. Methods: Data from the National Health and Nutrition Examination Survey (NHANES) in the year cycle of 1999-2018 were collected. HRR was calculated as the ratio of hemoglobin divided by the RDW. The outcomes were CVD, including stroke, congestive heart failure, atherosclerotic cardiovascular diseases (ASCVD), coronary artery disease as well as all-cause death including cardiovascular death and non-cardiovascular death. Univariate and multivariate analyses were performed to explore the association between HRR and outcomes. Restricted cubic spline curves were delineated. Results: In total, 47,719 participants were eligible for further analysis. In multivariate analysis adjusting for all confounding factors, higher HRR levels were significantly associated with a decreased risk of CVD. Compared to Q1 (<9.86), the odds ratio (OR) and 95% confidence intervals (95% CI) in Q2 (9.86-10.96), Q3 (10.96-11.97), and Q4 (≥11.97) were 0.79 (0.66, 0.94), 0.59 (0.48, 0.73), and 0.53, (0.42, 0.67), respectively, for predicting CVD. Similar results were observed for different subtypes of CVD, including stroke, congestive heart failure, and ASCVD. Notably, for predicting coronary heart disease, only Q3 was significant compared to Q1 (0.70, [0.54, 0.92], p = 0.010). HRR was significant for predicting all-cause death, cardiovascular death, and non-cardiovascular death. Additionally, HRR had the highest discriminative ability for predicting all-cause death compared with that of hemoglobin and RDW. Conclusions: A higher HRR was associated with a lower risk of CVD and death. Moderate levels of HRR were associated with the lowest risk for coronary heart disease. HRR had better discriminative ability than hemoglobin and RDW.