Rate of Asthma Prescriptions for Children and Adolescents During the 2018 Floods in Japan

To examine the association between a natural disaster and subsequent incidence of new asthma inhaler prescriptions among affected and unaffected children and adolescents after the 2018 Japanese floods.The study population included 1 073 170 people aged 0 to 19 years with no record of asthma treatment in the year prior to the flood; 4425 of these people were defined as victims of flooding.A retrospective cohort study using the National Health Insurance Claims Database in Japan. Between victims and nonvictims, the cumulative incidence of newly prescribed asthma inhalers in the 12 months following the flood (July 2018 to June 2019) was compared.In the year prior to the disaster, asthma inhaler use was no different between the victim and nonvictim group. In the year following the flooding disaster, victims were more likely to have a new inhaler prescription compared with nonvictims, with an adjusted hazard ratio of 1.30 (CI 1.16–1.46); 6.5% of victims compared with 5.6% of nonvictims were prescribed new asthma inhalers, suggesting a new asthma diagnosis. The prevalence of new prescriptions was significantly higher among victims in the 10- to 14-year and 15- to 19-year age groups, but no significant difference was seen in the 0- to 4-year and 5- to 9-year age groups. Rescue inhaler prescription rates did not differ between the 2 groups, but controller inhaler prescription rates were significantly higher in the victim group in all compared age groups.Natural disasters may be linked to an increased incidence of asthma, as evidenced by the 2018 Japan floods.As the frequency of serious natural disasters increases, the long-term health impacts remain uncertain. This study contributes to growing evidence that natural disasters cause more than short-term impacts and may lead to the development or exacerbation of chronic diseases such as asthma. Future research and public health surveillance will be paramount in fully understanding the long-term impacts these disasters can impart on the health of at-risk individuals and the overall population.