Incidence, prevalence, and treatment of Moyamoya disease in Japan: A population-based descriptive study

Background: Moyamoya disease (MMD) is characterized by progressive stenosis or occlusion of the terminal portions of the bilateral internal carotid arteries. A Japanese survey in 2003 reported an incidence and prevalence of MMD of 0.54 and 6.03 per 100,000 people, respectively, showing an upward trend over previous surveys. An update to these estimates is therefore warranted. Additionally, evidence is lacking on trends in revascularization and antiplatelet therapy in MMD patients. Methods: We conducted a population-based descriptive study using a Japanese claims database. From fiscal year (FY) 2015 to 2019, we standardized the incidence and prevalence estimates of MMD to the 2015 Japanese census population by age and sex. We also estimated the 1-year cumulative incidence of revascularization among incident MMD patients and the proportion of prevalent MMD patients receiving antiplatelet therapy in each FY. Results: The age-standardized male-to-female ratio of both incident and prevalent MMD patients was approximately 1:2. Standardized incidence and prevalence of MMD per 100,000 population increased slightly from 1.8 to 2.4 and 14.7 to 17.6, respectively. The 1-year cumulative incidence of revascularization among incident MMD patients varied between 21.9 % and 28.9 %. Among prevalent MMD patients, 36.6 % to 39.0 % received antiplatelet therapy. Conclusions: The incidence and prevalence of MMD in Japan from FY 2015 to 2019 were higher than those estimated in 2003. The trends in revascularization and antiplatelet therapy identified in this study will be useful in further improving the quality of MMD clinical practice.