The prevalence of fibromyalgia in the general population - a comparison of the American College of Rheumatology 1990, 2010 and modified 2010 classification criteria.
Background The ACR 1990 fibromyalgia classification criteria are based on widespread pain and tenderness. In 2010 new criteria were proposed, focusing more on multiple symptoms and these, latterly, were modified to require only self-report. The current study aimed to determine the population prevalence of fibromyalgia, and to compare differences in prevalence, using the alternative criteria. Methods A cross-sectional survey was conducted. Questionnaires, including items on pain, symptoms, and rheumatological diagnoses, were mailed to 4600 adults in northeast Scotland. Participants with chronic widespread pain, or who met the modified 2010 criteria, plus a sub-sample of other participants were invited to a research clinic. Attendees completed an additional questionnaire, and a rheumatological examination, and were classified according to the ACR 1990, 2010 and modified 2010 criteria. The prevalence of each was calculated, weighting back to the target population by age, sex and area of residence. Results Of 1604 questionnaire participants, 269 were invited and 104 (39%) attended the research clinic, of whom 32 (31%) met ?1 of the fibromyalgia criteria. The prevalence of fibromyalgia using the 1990, 2010 and modified 2010 criteria was 1.7% (95%CI: 0.7-2.8%); 1.2% (0.3-2.1%); and 5.4% (4.7-6.1%), respectively. The female/male ratio was 13.7 to 4.8 and 2.3, respectively. Conclusion Fibromyalgia prevalence varies with the different classification criteria - specifically, prevalence is higher, and a greater proportion of men are identified, with the modified 2010 criteria, compared to those requiring clinician input. This has important implications for the use of the new criteria both in research and in clinical practice. © 2014 American College of Rheumatology.