Hematocrit and the incidence of stroke: a prospective, population-based cohort study

BACKGROUND AND PURPOSE: Whether higher hematocrit levels could increase the incidence of stroke has always been full of controversy. This study aimed to explore the association between hematocrit and the incidence of stroke in the Chinese population. SUBJECTS AND METHODS: The Kailuan study is a prospective longitudinal cohort study on risk factors and events of chronic diseases. Using a multivariable Cox proportional hazards analysis, we examined the association between baseline hematocrit values and the incidence of stroke in the Kailuan cohort (93,299 participants). RESULTS: A total of 3,624 participants developed stroke during the 9-year follow-up period. In Cox regression models adjusted for demographic information and for clinical variables, there was a significant association between baseline hematocrit levels and the incidence of stroke. The highest hematocrit quartile (quartile 5: men, hematocrit >48.6%; women, hematocrit >43.2%) was associated with a higher incidence of stroke (HR 1.17, 95% CI 1.04–1.31, P for trend =0.0016) compared with the lowest hematocrit quartile (quartile 1: men, hematocrit <41.5%; women, hematocrit <36.6%). In the analysis of ischemic stroke, intracerebral hemorrhage separately, similar association was observed in ischemic stroke, but there were no statistical differences in intracerebral hemorrhage. CONCLUSION: Higher hematocrit levels are associated with a higher incidence of stroke in the Chinese population.