Prevalence of primary fibromyalgia in the Finnish population.

OBJECTIVE: To obtain descriptive epidemiological data on fibromyalgia and its components in a representative sample of the Finnish population. DESIGN: Cross sectional study of 8000 Finns aged 30 or more invited for screening and a main examination for musculoskeletal disorders and other major disorders. SETTING: A mobile clinic. POPULATION: 7217 subjects who attended the screening phase; 3434 subjects positive on screening who attended the main examination for musculoskeletal disorders. MAIN OUTCOME MEASURES: Musculoskeletal, mental, and other symptoms detected by interview and questionnaire; results of standardised clinical examination of the musculoskeletal system; operational definition of fibromyalgia; mortality at 10 years. RESULTS: The prevalence of fibromyalgia was low (54 cases; 0.75%) and related to age (peak prevalence at 55-64 years), female sex (twice as prevalent in women), occupation (no cases among 1596 white collar professionals), level of education (strong inverse gradient), and high levels of physical stress at work. No significant associations were found with body mass index, smoking, or mental stress at work. The prevalence of fibromyalgia was sensitive to even minor modifications of the definition. Fibromyalgia was strongly coincident with many other disorders, especially musculoskeletal conditions. Fibromyalgia did not predict mortality. CONCLUSION: Descriptive epidemiological data offer little support for the concept of fibromyalgia.