Increased risk of migraine in patients with psoriasis: A Danish nationwide cohort study.

BACKGROUND Psoriasis and migraine are common conditions with potential overlap of pathophysiological mechanisms. Both these diseases have been associated with increased cardiovascular risk but little is known about their interplay. OBJECTIVE We sought to investigate the link between psoriasis, and the risk of new-onset migraine, in a nationwide cohort of the Danish population. METHODS Data on all Danish citizens aged 18 years or older from January 1, 1997, to December 31, 2011, were linked at individual-level in nationwide registers. Incidence rates per 1000 person-years were calculated and crude and adjusted incidence rate ratios were estimated by Poisson regression models. RESULTS The study comprised a total of 5,379,859 individuals, including 53,006 and 6831 patients with mild and severe psoriasis, respectively, and 6243 patients with psoriatic arthritis. Fully adjusted incidence rate ratios for migraine were 1.37 (95% confidence interval 1.30-1.45), 1.55 (95% confidence interval 1.29-1.86), and 1.92 (95% confidence interval 1.65-2.22) for mild psoriasis, severe psoriasis, and psoriatic arthritis, respectively. Stratification for sex revealed increased risk of migraine in both male and female patients. LIMITATIONS We were unable to distinguish between subtypes of migraine, eg, migraine with and without aura. CONCLUSIONS Psoriasis was associated with a disease severity-dependent increased risk of migraine independent of measured confounders. Further studies are warranted to determine the effects of antipsoriatic treatment on this association, and whether migraine modifies the psoriasis-associated risk of cardiovascular disease.