Contemporary Epidemiology of Intracerebral Hemorrhage in Japan: A Population-Based Study from the Shiga Stroke and Heart Attack Registry.

Background

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Purpose

Intracerebral hemorrhage (ICH) remains a major cause of stroke-related mortality and disability, particularly in East Asian populations. However, contemporary population-based data regarding ICH incidence in Japan are limited. We investigated the incidence and clinical characteristics of ICH using a large population-based registry in Japan.

Methods

We analyzed patients with first-ever ICH registered in the Shiga Stroke and Heart Attack Registry between 2011 and 2015. Age- and sex-standardized incidence rates were calculated using the 2015 Japanese Population Census as the standard population.

Results

A total of 3,461 patients with first-ever ICH were identified during the study period, representing 7,008,831 person-years of observation and corresponding to a crude incidence rate of 49.4 per 100,000 person-years. Mean age at onset was 72±14 years, and 1,894 patients (54.7%) were men. The age-standardized incidence rate of ICH was 61.2 (95% confidence interval [CI], 60.5-61.8) per 100,000 person-years in men and 49.8 (95% CI, 49.3-50.4) per 100,000 person-years in women. Incidence increased markedly with age in both sexes. Women had more severe neurological status at presentation and worse functional outcomes at discharge, likely reflecting differences in age and baseline characteristics. Putaminal hemorrhage was the most common hemorrhage location in men, whereas subcortical hemorrhage was most common in women.

Conclusions

ICH remains a substantial public health burden in Japan, particularly among older individuals. Significant sex differences were observed in incidence, severity, functional outcomes, and hemorrhage location. Continued epidemiological surveillance of ICH is warranted in aging populations.