Increased risk of rheumatoid arthritis in patients with migraine: a population-based, propensity score-matched cohort study.

Previous cross-sectional studies have suggested an association between migraine and rheumatoid arthritis (RA), but no longitudinal study has been performed to evaluate the temporal relationship between the two conditions. The purpose of the present population-based, propensity score-matched cohort study was to investigate whether migraineurs are at a higher risk of developing RA. A total of 58,749 subjects aged between 20 and 90 years with at least two ambulatory visits with a diagnosis of migraine were recruited in the migraine group. We fit a logistic regression model that included age, sex, comorbid conditions, and socioeconomic status as covariates to compute the propensity score. The non-migraine group consisted of 58,749 propensity score-matched, randomly sampled subjects without migraine. The RA-free survival curves were generated using the Kaplan-Meier method. Stratified Cox proportional hazard regression was used to estimate the effect of migraine on the risk of RA. During follow-up, 461 subjects in the migraine group and 220 in the non-migraine group developed RA. The incidence rate of RA was 3.18 (95% confidence interval [CI] 2.90-3.49) per 1000 person-years in the migraine group and 1.54 (95% CI 1.34-1.76) per 1000 person-years in the non-migraine group. Compared to the non-migraine group, the crude hazard ratio of RA for the migraine group was 2.15 (95% CI 1.82-2.56, P < 0.0001), and the multivariable-adjusted hazard ratio was 1.91 (95% CI 1.58-2.31, P < 0.0001). This study showed that patients with migraine had an increased risk of developing RA.