Surveillance of First-Generation H1-Antihistamine Use for Older Patients with Dementia in Japan: A Retrospective Cohort Study

BACKGROUND: This study aimed to investigate the rate of first-generation H1-antihistamines use for older adults with dementia in Japan. METHODS: The study design was retrospective cohort using claims data between fiscal years 2010 and 2013. Subjects were 75 years or older, diagnosed with dementia, and given H1-antihistamines orally during the study period after being diagnosed with dementia. We investigated the cumulative number of oral H1-antihistamines administered and the relationship between first-generation H1-antihistamine use and each explanatory variable using crude and adjusted odds ratio. RESULTS: The cumulative total for use of first-generation H1-antihistamine for older adults with dementia accounted for 32.1% of all antihistamine medication. The majority of first-generation H1-antihistamine prescriptions were indicated for cold treatment. Those with upper respiratory infection or asthma had a significantly positive relationship with first-generation H1-antihistamine use. CONCLUSION: The study showed that first-generation H1-antihistamine drugs were highly prescribed in older adults with dementia in Japan.