To examine some of the psychometric properties of the Spanish version of the FibroFatigue Scale (FFS).
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.
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-5D (-.48, P<.01) and the HADS depression subscale (.25, P<.01), but not with the HADS anxiety subscale.
These results support the reliability and validity of the data obtained with the Spanish version of the FSS.