Elevated red cell distribution width and cardiovascular mortality in ASCVD risk cohorts: National Health and Nutrition Examination Survey (NHANES III).

Background: Although red cell distribution width (RDW) is associated with increased cardiovascular mortality, the relationship between an elevated RDW and cardiovascular mortality among various ASCVD risk groups is unknown.

Methods: We utilized the National Health and Nutrition Examination Survey (NHANES) III, which uses a complex, multistage, clustered design to represent the civilian, community-based US population. Out of 30,818 subjects whose data were entered during the 1988-1994 period, 8884 subjects over 40 years of age, representing a weighted sample of 85,323,902 patients, were selected after excluding missing variables. The ACC/AHA pooled cohort equation (PCE) was used to calculate atherosclerotic cardiovascular disease (ASCVD) risk, and low (<7.5%), intermediate (7.5-20%), and high (>20%) risk groups were created. The primary endpoint was cardiovascular mortality. A multivariate proportional hazard regression was performed using the Fine and Gray (sub-distribution) method. Red cell distribution (RDW), C-reactive protein (CRP), age, sex, race, diabetes, smoking status, high-density lipoprotein (HDL), and chronic kidney disease (CKD) were used as covariates in each of the ACC/AHA pooled cohort risk groups.

Results: The adjusted hazard ratios for RDW >14 (Normal range 12.5-14.5 %) as compared to <13 were 2.79 (95% confidence intervals (95% CI) 2.77-2.81, < 0.01), 2.02 (95% CI 2.01-2.02, < 0.01), 1.18 (95% CI 1.18-1.18, < 0.01) in the low, intermediate and high-risk groups respectively. The 20-year cumulative cardiovascular mortality (RDW >14 vs. <13) was 4% vs. 1.3% low, 17.7% vs. 7.7% in intermediate and 28.1% vs. 24.6% in high ASCVD risk groups respectively.

Conclusion: Our findings support that measurement of RDW in the intermediate ASCVD group may be clinically valuable for further risk stratification and prognostication in the general population of people aged more than 40 years of age with regards to identifying those at an increased risk for cardiovascular mortality.