The London fibromyalgia epidemiology study: The prevalence of fibromyalgiasyndrome in London, Ontario

Objective. To estimate the point prevalence of fibromyalgia syndrome (FM) a mong noninstitutionalized Canadian adults; and to assess the effect of demo graphic variables on the odds of having FM. Methods. A screening questionnaire was administered via telephone to a rand om community sample of 3395 noninstitutionalized adults residing in London, Ontario. Individuals screening positive were invited to be examined by a r heumatologist to confirm or exclude FM using the 1990 American College of R heumatology classification criteria. Results. One hundred confirmed cases of FM were identified, of whom 86 were women. Mean age among FM cases was 49.2 years among women, 39.3 years amon g men (p < 0.02). FM affects an estimated 4.9% (95% CI 4.7%, 5.1%) of adult women and 1.6% (1.3%, 1.9%) of adult men in London, for a female to male r atio of roughly 3 to one. In women, prevalence rises steadily with age from < 1% in women aged 18-30 to almost 8% in women 55-64. Thereafter, it decli nes. The peak prevalence in men also appears to be in middle age (2.5%; 1.1 %, 5.7%). FM affects 3.3% (3.2%, 3.4%) of noninstitutionalized adults in Lo ndon. Female sex, middle age, less education, lower household income, being divorced, and being disabled are associated with increased odds of having FM. Conclusion. FM is a common musculoskeletal disorder among Canadian adults, especially among women and persons of lower socioeconomic status.