Sickness absence among female employees with migraine and co-existing conditions.

This prospective cohort study examined the risk of sickness absence among 27,127 female public-sector employees by status of migraine and co-existing conditions. A baseline survey was used to assess chronic disorders and demographic factors. Information on sickness absence in the 3 years following the survey was obtained from employers' registers. Migraine was related to 5.4 extra sickness absence days per person-year, with the corresponding figures being 14.6 and 6.1 for depression and respiratory disorders, respectively. After adjusting for age, marital status, socioeconomic status and presence of depression or respiratory disorders, employees with migraine had a 1.21 (95% confidence interval 1.18, 1.24) times higher risk of self-certified sickness absence episodes (< or = 3 days) than did those without migraine. The corresponding excess risk for medically certified absence episodes (> 3 days) was 1.15 (1.12, 1.19). Among employees with depression or respiratory disorders, secondary migraine was associated with an increased risk of sickness absence episode of 1.15 to 1.23. These findings suggest that migraine is associated with increased risk of recorded sickness absence independent of depression and respiratory disorders.