Regional differences in the incidence of asthma exacerbations in Japan: A heat map analysis of healthcare insurance claims data.

Abstract Background In Japan, regional differences in asthma mortality have been reported; however, regional differences in asthma exacerbations have not been studied extensively. Therefore, using a health insurance claims database, we investigated the regional differences in the incidence of asthma exacerbations in Japan. Methods This study used data from Medi-Scope (Japan Medical Information Research Institute Inc., Japan)—a nationwide health insurance claims database. Patients with asthma at the index date (the latest date of an asthma-related prescription with an asthma diagnosis before October 1, 2018) were included in the analysis. The pre-index period was defined as 1 year before the index date, and the follow-up period as 1 year after the index date. The incidence of asthma exacerbation events was analyzed for each region. Results The primary analysis population comprised 24,883 patients who were continuously prescribed ICS or ICS/LABA at least four times during the pre-index period. The incidence rate of asthma exacerbations with hospitalization was the highest in Chugoku (2.95/100 person-years [95% CI, 1.97–4.43]) and the lowest in Kanto (1.52/100 person-years [95% CI, 1.26–1.83]). The incidence rate of asthma exacerbations for the composite outcome of hospitalization, injectable corticosteroid prescription, and oral corticosteroid burst was the highest in Fukui (105.00/100 person-years [95% CI, 64.53–170.85]) and the lowest in Nagasaki (15.69/100 person-years [95% CI, 10.84–22.72]). Conclusions Regional differences in the incidence of asthma exacerbations as well as their treatments were observed in Japan.