Fibromyalgia syndrome (FMS) is a painful condition of unknown etiology, highly prevalent, and associated with other conditions, which causes great impact on daily life and quality of life. OBJECTIVE: To assess, due to the multifactorial character of the FMS, the discriminating power of instruments used to identify good indicators of self-assessment and self-knowledge. PATIENTS AND METHODS: This is a descriptive, exploratory, comparative, cross-sectional study with quantitative approach, and sample comprising a treatment group (T), diagnosed with FMS (n = 63) and a control group (C), undergoing interconsultation at the Pain Outpatient Clinic (n = 75). The following instruments were used: Fibromyalgia Impact Questionnaire (FIQ); visual analogue scale (VAS); McGill Pain Questionnaire; and the Post-Sleep Inventory (PSI). To evaluate the quality of life, Medical Outcomes Study 12-item Short-Form Health Survey (SF-12) was used. RESULTS: In the two groups, female gender predominated. The mean age of the sample was 42.3 ± 4.3 years, 45% were married, and the average schooling was 8 ± 3.5 years. The mean duration of pain was 3.2 years, and a mean time of two years were required for the clinical diagnosis of FMS in group T. Group T had higher levels of pain, anxiety, and depression, worse quality of sleep, less flexibility, and worse quality of life, although some of these symptoms were also present in group C. CONCLUSIONS: All instruments had good discriminating power (P < 0.05), especially FIQ, VAS and PSI, whose areas under the ROC curve were greater
fibromyalgia; quality of life; evaluation; pain clinics
