Increased risk of hemorrhagic stroke in patients with migraine: a population-based cohort study.

Objective: Previous studies on the association between migraine and the risk of developing hemorrhagic stroke (HS) have generated inconsistent results. The aim of the present population-based, age- and sex- matched follow-up study was to investigate whether migraine is associated with an increased risk of HS.

Method: A total of 20925 persons with at least two ambulatory visits in 2001 with the principal diagnosis of migraine were enrolled in the migraine group. The non-migraine group consisted of 104625, age- and sex- matched, randomly sampled subjects without migraine. The two-year HS-free survival rates for these 2 groups were estimated using the Kaplan-Meier method. Cox proportional hazards regression was used to estimate the effect of migraine on the occurrence of HS.

Results: During the 2 year follow-up, 113 subjects in the migraine group (0.54%) and 255 in the non-migraine group (0.24%) developed HS. The crude hazard ratio (HR) for developing HS in the migraine group was 2.22 compared to the non-migraine group (95% confidence interval [CI]: 1.78-2.77, p<0.0001) and the adjusted HR was 2.13 (95% CI: 1.71-2.67, p<0.0001) after controlling for demographic characteristics and comorbid medical disorders.

Conclusions: This population-based age- and sex- matched cohort study shows that migraine was linked to an increased risk of HS.