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,
p 0.01), 2.02 (95% CI 2.01–2.02, p 0.01), 1.18 (95%
CI 1.18–1.18, p 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.