Seasonal Variations in Triptan Prescription in Japan: A Nationwide Time-Series Analysis

Objective: This study aimed to investigate seasonal differences in migraine onset in Japan and associated trends in the prescription of triptan.

Background: The relationship between seasonal changes and the onset of migraine remains largely unknown.

Methods: We combined the large-scale medical claims data in Japan with city-level meteorological data presented by the Japan Weather Association. The study period was from January 2018 to December 2019. We included patients aged 18-74 years and diagnosed with migraine who had been prescribed triptans in 2018. Patients were categorized into four groups according to the seasons when they were prescribed medicines: winter (January-March), spring (April-June), summer (July-September), and autumn (October-December). Migraine onsets were defined by the time of triptan prescription. The least-square mean differences between the seasons were estimated with linear mixed-effects models for repeated measures, adjusting for the following covariates: sex, age, acute migraine medications, and medications for migraine prevention, comorbidities that can induce migraine, other comorbidities, and the estimated age of menopause in females.

Results: We analyzed data of 12,986 patients in 2019 after triptan had been prescribed (female 74.1%). The mean age was 44.1 years. The mean number of amounts of prescriptions comprised 2.12 tablets/month in spring and summer, whereas there were only 2.09 tablets/month in autumn and 2.00 tablets/month in winter. The amount of triptan prescribed in winter was lower than in spring (β = -0.117; 95% confidence interval [CI]: -0.169 to -0.065).

Conclusion: The study results suggest that seasons can have an impact on the onset of migraine; thus, clinicians may advise patients to take preventive actions, including self-care and drug therapies, from the winter stage. This should be done in order to reduce the number of migraine onsets in high-risk season (spring) regardless of region.