The London Fibromyalgia Epidemiology Study: the prevalence of fibromyalgia syndrome in London, Ontario.

Abstract

To estimate the point prevalence of fibromyalgia syndrome (FM) among noninstitutionalized Canadian adults; and to assess the effect of demographic variables on the odds of having FM. A screening questionnaire was administered via telephone to a random community sample of 3395 noninstitutionalized adults residing in London, Ontario. Individuals screening positive were invited to be examined by a rheumatologist to confirm or exclude FM using the 1990 American College of Rheumatology classification criteria. 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 among 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 ratio 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 declines. 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 London. Female sex, middle age, less education, lower household income, being divorced, and being disabled are associated with increased odds of having FM. FM is a common musculoskeletal disorder among Canadian adults, especially among women and persons of lower socioeconomic status.