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

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. 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. 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]). Regional differences in the incidence of asthma exacerbations as well as their treatments were observed in Japan. [Display omitted]