COPD prescription patterns after the 2018 Japan floods: analysis of national data.

Climate change has led to an increase in flood disasters worldwide, raising concerns about their potential impact on respiratory health. This study investigated the impact of the 2018 Japan Floods, one of the largest flood disasters in Japan's history, on prescription rates for chronic obstructive pulmonary disease (COPD). To examine the impact of the disaster on COPD-related prescriptions, we analysed anonymised health insurance claims data from the Japanese National Database. The study focused on residents of three prefectures that included the most severely affected areas during the 2018 Japan Floods, covering a 2-year observation period-1 year before and 1 year after the disaster. First, we compared new prescriptions of long-acting inhaled COPD medications after the disaster between victims and non-victims among individuals who had not received such prescriptions during the previous year (n = 3,674,535). Second, we examined prescriptions for antibiotics or systemic steroids after the disaster among individuals already receiving long-acting inhaled COPD medications before the disaster (n = 18,059), as indicators of COPD exacerbations. Cox proportional hazards models showed that new prescriptions for long-acting inhaled COPD medications were significantly higher among disaster victims than among non-victims in the year following the 2018 Japan Floods (aHR: 1.56; 95% CI [1.25-1.95]). Difference-in-differences analysis showed that exacerbation-related prescriptions significantly increased among disaster victims compared with non-victims (aROR: 1.50; 95% CI [1.06-2.11]). New prescriptions for COPD controller medications and exacerbation-related prescriptions significantly increased in populations affected by the 2018 Japan Floods.