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.