Abstract
BACKGROUND: Little is known about the effect of fibromyalgia on absence due to sickness in working populations. OBJECTIVE: To examine the risk of absence due to sickness among employees with fibromyalgia. METHODS: A prospective cohort study with 1-year follow-up of recorded and certified absence due to sickness after a survey of chronic diseases among 34 100 Finnish public sector employees (27 360 women and 6740 men) aged 17-65 years at baseline in 2000-2. RESULTS: 20 224 days of absence due to sickness for the 644 employees with fibromyalgia and 454 816 days for others were documented. Of those with fibromyalgia, 67% had co-occurring chronic conditions such as osteoarthritis, rheumatoid arthritis, depression or other psychiatric disorders. Compared with employees with none of these chronic conditions, the hazard ratio (HR) adjusted for age, sex and occupational status was 1.85-fold (95% confidence interval (CI) 1.53 to 2.18) for people with fibromyalgia alone and 2.63-fold (95% CI 2.34 to 2.96) for employees with fibromyalgia with coexisting conditions. The excess rate of absence due to sickness was 61 episodes/100 person-years among people with fibromyalgia alone. Among employees with musculoskeletal and psychiatric disorders, secondary fibromyalgia was associated with a 1.4-1.5-fold increase in risk of absence. CONCLUSION: Fibromyalgia is associated with a substantially increased risk of medically certified absence due to sickness that is not accounted for by coexisting osteoarthritis, rheumatoid arthritis or psychiatric disorders.