Association between migraine and risk of venous thromboembolism: A nationwide cohort study

Background .—The link between arterial thromboembolism and migraine is well‐documented; however, few studies investigated the link between venous thromboembolism (VTE) and migraine. We aimed to evaluate the association between migraine and VTE and to examine whether demographics or comorbid risk factors modulate VTE development. Methods. —We conducted a cohort study accessing a nationwide claims‐based database with an adult cohort of 102,159 neurologist‐diagnosed migraine patients, and 102,159 nonheadache comparison subjects, matched on sex and propensity score for the diagnosis of migraine. Both cohorts were followed until the end of 2010, death, or VTE development. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were calculated based on Cox proportional hazards regression analyses and compared between the two groups. Results .—During a mean follow‐up period of 4.2 years, VTE developed in 226 patients (460,047 person‐years) in the migraine cohort and in 203 subjects (462,401 person‐years) in the comparison cohort. Overall, likelihood of VTE for the migraine cohort did not differ from that in the comparison cohort (aHR 1.12; 95% CI, 0.92–1.35; P = .251). However, subgroup analysis by migraine subtypes (P = .004 for interaction) revealed an elevated risk of VTE in patients with migraine with aura (aHR 2.42; 95% CI, 1.40–4.19; P = .002), but not in those with migraine without aura. The association was not altered in subsequent subgroup analyses and sensitivity analyses. Conclusions Risk of VTE development is elevated specifically in patients diagnosed with migraine with aura. This association suggests a linked disease mechanism and warrants further exploration.