Psychometric Properties of the Fibromyalgia Survey Questionnaire in Chilean Women With Fibromyalgia

The aim of this study was to evaluate the psychometric properties of the Chilean version of the Fibromyalgia Survey Questionnaire (FSQ).

Women with fibromyalgia (FM; n = 214), women with rheumatoid arthritis (RA; n = 97), and women without chronic pain (being followed by Gynecology, G; n = 117) from the Red de Salud UC CHRISTUS (Santiago, Chile) participated. Women with FM completed the FSQ, Fibromyalgia Impact Questionnaire (Revised Version), Numerical Pain Rating Scale, Pain Catastrophizing Scale, Pain Vigilance and Awareness Questionnaire, Patient Health Questionnaire 15, and Short-Form Health Survey. Two weeks later, they completed the FSQ again by phone (n = 120).

The FSQ total scale showed excellent to good internal consistency at T1 (α = 0.91, ω = 0.91) and T2 (α = 0.78, ω = 0.78), and good test-retest reliability (intraclass correlation coefficient, 0.79; 95% confidence interval [CI], 0.72-0.85). It showed medium to large correlations with the other measures. Discriminant analysis between the FM group and the control group (RA and G) revealed that the FSQ total scale reached a classification accuracy of 81.3%. Receiver operating characteristic curve (adjusted area under the curve, 0.88; 95% CI, 0.85-0.92) showed that the best FSQ cutoff was 17, resulting in sensitivity of 89% (95% CI, 0.84-0.93) and specificity of 75% (95% CI, 0.69-0.80). Considering the FM diagnosis performed by a rheumatologist as the criterion standard, sensitivity and specificity of the modified 2010 American College of Rheumatology preliminary criteria for FM were 92.8% (95% CI, 0.88-0.96) and 63.4% (95% CI, 0.57-0.70), respectively.

The Chilean version of the FSQ presents good psychometric properties and is a useful tool in clinical settings to assist in FM diagnosis and symptom assessment. A cutoff score of 17 or higher seems to be the most appropriate for Chilean population.