LAUSR

PURPOSE To compare functional and clinical variables of women with fibromyalgia (American College of Rheumatology [ACR] criteria) vs women diagnosed by doctors and women with knee osteoarthritis (KOA). METHODS This is a cross-sectional study. We used clinical measures, namely, Widespread Pain Index (WPI), Symptom Severity Scale (SSS), Fibromyalgia Impact Questionnaire-Revised (FIQ-R), Numerical Pain Rating Scale (NPRS), Central Sensitization Inventory (CSI), Pain-Related Catastrophizing Thoughts Scale (PCTS), and functional measures, such as Sit-to-Stand (STS) test, and Timed Up and Go (TUG) test. RESULTS The sample consisted of 91 participants divided into 3 groups: participants with KOA (n = 30), fibromyalgia diagnosed according to the ACR (FM-ACR, n = 31), and fibromyalgia according to the medical diagnosis (FM-Med, n = 30). In the comparisons, we observed a significant difference (P < 0.05) and a large effect size (d ≥ 0.8), between all groups, in the WPI, WPI + SSS, FIQ-R domains, CSI, and PCTS. We did not observe significant values in the correlations between the clinical variables, SST, and TUG test. CONCLUSION People with fibromyalgia according, to the ACR, have higher levels of widespread pain, symptom severity, global impact on quality of life, central sensitization, and catastrophizing compared with people with knee OA and people with clinical fibromyalgia diagnosis not confirmed by the ACR diagnostic criteria.