Risk factors for intracerebral hemorrhage by five specific bleeding sites: Japan Public Health Center-based Prospective Study.

Background: Evaluating the risk factors for intracerebral hemorrhage is indispensable for primary prevention. However, the pathogenesis varies depending on the bleeding site, and few prospective studies have explored risk factors in detail for each site.

Participants and methods: The Japan Public Health Center-based Prospective Study is a prospective study comprising a population-based sample of Japanese adults in 1990 (Cohort I) and in 1993 (Cohort II). A total of 34,137 participants (11,907 men and 22,230 women) were enrolled in this study and followed up until 2009 for Cohort I and until 2012 for Cohort II. The association between risk factors (age, sex, blood pressure, serum cholesterol, triglycerides, blood glucose, body mass index, smoking, and drinking status) and intracerebral hemorrhage by its bleeding site (lobes, putamen, thalamus, cerebellum, and brainstem) was assessed using Cox proportional hazards analysis.

Results: During a median 20-year follow-up, 571 intracerebral hemorrhage events occurred. Hypertension was associated with an increased risk of total intracerebral hemorrhage, but not lobar hemorrhage. The multivariable hazard ratio (95% confidence intervals) was 2.09 (1.75-2.50) for total intracerebral hemorrhage. In contrast, a low serum total cholesterol level was associated only with lobar hemorrhage (1.73 (1.01-2.96)). Heavy drinking was associated with the risk of total and putamen hemorrhage, and obesity was associated with the risk of putamen hemorrhage.

Discussion and conclusion: The present study identified different risk factors depending on the bleeding site of intracerebral hemorrhage.