Cardiovascular fitness and risk of migraine: a large, prospective population-based study of Swedish young adult men

Objectives To examine the longitudinal relationship between cardiovascular fitness in young adult men and future risk of migraine and to estimate eventual differential effects among categories of body mass index (BMI) and blood pressure. Design National, prospective, population-based cohort study. Setting Sweden 1968-2014. Participants 18-year-old Swedish men (n=1 819 828) who underwent mandatory military conscription examinations during the years 1968-2005. Primary and secondary outcomes The primary outcome was the first dispensation of prescribed migraine-specific medication, identified using the Swedish Prescribed Drug Register. The secondary outcome was documented migraine diagnosis from the Swedish National Hospital Register. Results During follow-up, 22 533 men filled a prescription for migraine-specific medication. After confounding adjustment, compared with high cardiovascular fitness, low and medium fitness increased the risk of migraine-specific medication (risk ratio (RR)(low): 1.29, 95%CI 1.24 to 1.35; population attributable fraction: 3.6%, 95%CI 1.7% to 5.3% and RRmedium: 1.15, 95%CI 1.12 to 1.19; population attributable fraction: 8.0%, 95%CI 4.0% to 11.7%). To assess potential effect measure modification, stratified analyses of these association by levels of BMI and blood pressure showed that lower fitness levels increased risk of migraine across all groups except among underweight men or men with high diastolic blood pressure. Conclusions Young men with a lower cardiovascular fitness had a higher long-term risk of developing pharmacological prescription-requiring migraine. This study contributes with information regarding risk factors for migraine in men, an understudied population in migraine research.