Supplementary Material for: Trends in incidence of intracerebral hemorrhage and its bleeding sites from 1985 to 2017 in Japanese rural communities

Introduction: Evaluating long-term trends for the incidence of intracerebral hemorrhage is a priority for primary prevention. It is also important to assess the trends in the proportions of bleeding sites because the pathogenesis, prognosis, and operative procedures differ among them. Methods: A prospective community-wide stroke registry in two rural Japanese communities (Ikawa Town and Kyowa Town, with populations of approximately 5000 and 15,000, respectively) was conducted. The age-adjusted incidence of intracerebral hemorrhage from 1985 to 2017 was calculated by the direct method using the World Standard Population. The proportions of intracerebral hemorrhage by bleeding sites (putamen, thalamus, lobes, cerebellum, and brainstem) based on neuroimaging were calculated in each of the following three periods: 1985-1995, 1996-2006, and 2007-2017. Results: During the study period, 383 intracerebral hemorrhage events as first-ever strokes were registered. The age-adjusted incidence declined over time by 33%, with a large reduction between 1985-1989 and 1990-1994, but the magnitude of the decline has diminished since the 1990s. The proportions of bleeding sites were 37%, 29%, and 31% for putamen in 1985-1995, 1996-2006, and 2007-2017, respectively; the corresponding proportions were 24%, 35%, and 18% for thalamus; 10%, 10%, and 21% for lobes; 2%, 8%, and 12% for cerebellum; and 8%, 6%, and 5% for brain stem. Conclusion: The age-adjusted incidence declined by 33% from the 1990s with a large reduction in the early 1990s in Japanese rural communities. Among intracerebral hemorrhages, the proportion of bleeding sites decreased for the putamen, thalamus, and brain stem, and increased for lobes and the cerebellum.研究背景：评估脑出血（intracerebral hemorrhage）发病率的长期变化趋势是一级预防的核心任务。由于不同出血部位的发病机制、预后及手术术式均存在差异，分析出血部位占比的变化趋势同样具有重要临床意义。 研究方法：本研究针对日本两个农村社区——井川町与协和町（人口分别约为5000与15000），开展了一项前瞻性社区全人群卒中登记研究。采用世界标准人口（World Standard Population）直接法（direct method）计算1985年至2017年脑出血的年龄标化发病率（age-adjusted incidence）。基于神经影像学（neuroimaging）检查结果，将三个研究时段（1985-1995年、1996-2006年及2007-2017年）的脑出血按出血部位（壳核putamen、丘脑thalamus、脑叶lobes、小脑cerebellum及脑干brainstem）分别计算占比。 研究结果：本研究周期内共登记383例首次卒中相关脑出血事件。整体而言，年龄标化发病率随时间累计下降33%，其中1985-1989年至1990-1994年期间降幅最为显著，但自20世纪90年代以来，下降幅度逐渐收窄。各时段出血部位占比具体如下：壳核分别为37%、29%及31%；丘脑分别为24%、35%及18%；脑叶分别为10%、10%及21%；小脑分别为2%、8%及12%；脑干分别为8%、6%及5%。 研究结论：日本农村社区的脑出血年龄标化发病率在1985至2017年间累计下降33%，其中20世纪90年代早期降幅最为显著，此后下降幅度逐渐放缓。在各类脑出血中，壳核、丘脑及脑干出血的占比呈下降趋势，而脑叶及小脑出血的占比则有所上升。