The Spanish version of the FibroFatigue Scale:: validation of a questionnaire for the observer's assessment of fibromyalgia and chronic fatigue syndrome

Objective: To examine some of the psychometric properties of the Spanish version of the FibroFatigue Scale (FFS). Methods: FFS was administered to 120 patients diagnosed with fibromyalgia and chronic fatigue syndrome. Internal consistency was evaluated by using Cronbach's alpha, test-retest reliability with weighted kappa and construct validity by correlations among FFS, the Fibromyalgia Impact Questionnaire (FIQ), the EuroQol 5D (EQ-5D) and the Hospital Anxiety and Depression Scale (HADS). The interrater reliability was tested using analysis of variance with patients and raters as independent factors. Results: Internal consistency (alpha) was .88, test-retest reliability was .91, and interrater reliability was .93. Significant correlations were obtained between overall FFS and the FIQ (.55, P <.01), the EQ-513 (-.48, P <.01) and the HADS depression subscale (.25, P <.01), but not with the HADS anxiety subscale. Conclusion: These results support the reliability and validity of the data obtained with the Spanish version of the FSS. (c) 2006 Elsevier Inc. All rights reserved.