Assessing functional disability and health status of women with fibromyalgia: validation of a Hebrew version of the Fibromyalgia Impact Questionnaire

Abstract

Objective: To validate a translated version of the Fibromyalgia Impact Questionnaire (FIQ) to be used by Hebrew speaking populations.

Methods: We administered the FIQ to 100 women with fibromyalgia (FM). The FIQ measures physical functioning, work status, depression, anxiety, sleep, pain, stiffness, fatigue, and well being. All patients were asked about the presence and severity (assessed by visual analog scale) of relevant FM symptoms (pain, fatigue, anxiety, etc.); a count of 18 tender points was conducted by thumb palpation, and tenderness thresholds were assessed by dolorimetry. Test-retest reliability was assessed using Spearman correlations. Internal consistency was evaluated with Cronbach's alpha coefficient of reliability. To assess content validity a cutoff criterion of > or = 25% impairment responses was set to indicate a valid item. Construct validity of the FIQ was evaluated by correlating the physical functioning score as well as the separate items with measures of symptom severity, count of tender points, and tenderness thresholds.

Results: Test-retest reliability was r = 0.96 for physical functioning, and 0.80-0.96 for other items of FIQ. Internal consistency was alpha = 0.93 at Time 1 and 0.86 at Time 2. Seventeen of 19 items of the FIQ met the > or = 25% criterion. Significant moderate to high correlations were obtained between the FIQ items and severity symptoms, point count, and tenderness threshold.

Conclusion: The FIQ is a reliable and valid instrument for measuring functional disability and health status in Israeli women with FM.