High risk of developing subsequent epilepsy in young adults with migraine: a nationwide population-based cohort study in Taiwan

BACKGROUND AND PURPOSE: This study evaluated the effect of migraine on the subsequent development of epilepsy. METHODS: A total of 10,016 patients diagnosed with migraine [ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) 346] during the period between 2000 and 2009 who were aged older than 20 years were identified as the migraine cohort. A comparison cohort including 40 064 people were enrolled in this study. We calculated the adjusted hazard ratio (aHR) for developing epilepsy (ICD-9-CM 345) in the two cohorts after adjusting for age, sex and comorbidities. Kaplan-Meier analysis was used to measure the cumulative epilepsy incidence, and the log-rank test was used to estimate the differences between two curves. RESULTS: The cumulative incidence of epilepsy was significantly high in the migraine cohort. The aHR for developing epilepsy in the migraine cohort was 1.85 (95% CI = 1.22-2.81). The aHR for developing epilepsy in the female migraineurs was significantly different compared with that of the non-migraine cohort (aHR = 2.04, 95% CI = 1.20-3.48) and male migraineurs (aHR = 1.53, 95% CI = 0.78-3.00). The incidence of developing epilepsy was increased in patients aged 20-44 years, yielding an aHR of 2.14 (95% CI = 1.24-3.68). The comorbidity-specific aHR for developing epilepsy associated with migraine was 2.33 (95% CI = 1.25-4.34) in patients without any comorbidities, and 1.73 (95% CI = 1.02-2.93) in those with comorbidities. CONCLUSION: This population-based retrospective cohort study revealed a significant increase in subsequent epilepsy risk in young adults with migraine.