The 2018 Japan Floods increased prescriptions of anti-dementia drugs among disaster victims: a retrospective cohort study based on a national health insurance database

Abstract

BACKGROUND AND AIM: The occurrence of weather-related disasters is increasing with the progression of global climate change. Natural disasters increase the risk of impaired cognitive function of elderly victims. It is not clear what effects such natural disasters have on the prescriptions of drug treatment for dementia. Thus, we evaluated the effect of the 2018 Japan Floods, the second-largest water-related disaster in Japan, on the prescriptions of anti-dementia drugs (ADD) for elderly people. Methods: From the National Database of Health Insurance Claims, we extracted prescription data in Hiroshima, Okayama and Ehime prefectures for one year before and after the disaster. From the database, 1,710,119 people aged 65 years or over were selected as the study participants. Sex- and age-adjusted odds ratios (ORs) of victims for new ADD prescriptions were calculated using logistic regression models. A difference-in-difference analysis was conducted to take into account the trends for the ORs before the disaster. Furthermore, among continuous ADD users, the effects of disaster on the increasing trend for ADD prescriptions (daily dose or number of drug types) was also evaluated. Results: Of 1,710,119 people enrolled, 15,994 (0.9%) were recorded as a disaster-victims, and 112,289 (6.6%) were prescribed ADD. Among original non-users, victims were more likely to start using ADD after the disaster than non-victims [adjusted OR=1.33 (95% CI:1.16–1.52)]. Among continuous users, an increasing trend for ADD prescriptions was more often observed for victims than non-victims [1.61 (1.13–2.31)]. These associations were maintained even after considering the pre-disaster trend of ADD use. Conclusions: The natural disaster results in an increased number of users of anti-dementia medications. Special attention to such neurological shifts and welfare support is needed for elderly victims of a large-scale natural disaster.