Background Individual blood cell count abnormalities have been associated with cardiovascular disease and increased mortality. In this study, we defined a "cytopenia phenotype," reflecting bone marrow hypoproliferation, to determine if peripheral blood cytopenia is associated with increased cardiovascular disease and mortality risk. Methods and Results Study participants were derived from a biracial observational cohort study, REGARDS (Reasons for Geographic and Racial Differences in Stroke), that enrolled 30 239 Black and White participants aged ≥45 years between 2003 and 2007. Median follow up was ≈9 years. The current study included 19 864 participants from REGARDS study (37.9% men, 40% Black participants) who have complete blood count available at study enrollment. We defined a cytopenia phenotype based on age-, sex-, and race-adjusted lowest fifth percentile of blood counts. Multivariable Cox proportional hazards models estimated the hazard ratios (HR) and 95% CI of cytopenia for mortality and incident cardiovascular disease in adjusted models. Mean age of the study participants was 64 years (SD:9.7). The prevalence of cytopenia was 1.9% (n=378). Cytopenia was associated with increased risk of all-cause mortality (HR, 1.73; 95% CI, 1.34-2.22) and cardiovascular disease mortality (HR, 1.56; 95% CI, 1.11-2.29). Cytopenia was associated with stroke risk in Black but not White participants (HR, 1.96 versus 0.86; P-interaction for race=0.08) and was not associated with coronary heart disease risk. Conclusions We defined a cytopenia phenotype with clinical implications for mortality and stroke risk in a large biracial and geographically diverse population. Whether generated through somatic mutations or decreased organ function, cytopenia was associated with mortality risk and was a race-specific risk factor for stroke.
Keywords: cardiovascular disease; cytopenia; mortality; race; stroke.