Objective: To validate a translated Italian version of the Fibromyalgia Impact Questionnaire (FIQ).
Methods: The Italian version of the FIQ was administered to 50 patients affected by fibromyalgia (FM) (48 patients filled out the questionnaire again 10 days later) together with the Italian version of the Stanford Health Assessment Questionnaire (HAQ), the Medical Outcomes Survey Short Form-36 (SF-36), and a tender point count (TPC) obtained by summing the score (0-3) of each tender point tested by thumb palpation. All patients were asked about the severity of pain today (10 cm visual analog scale) and the duration of symptoms. Test-retest reliability was assessed using Spearman correlations. Internal consistency was evaluated with Cronbach's alpha of reliability. Construct validity of the FIQ was evaluated by correlations between the HAQ and subscales of the SF-36 as well as the TPC.
Results: The mean duration of symptoms was 6.5 years and the mean age of the participants was 57.4 years. Test-retest reliability was between 0.74 and 0.95 for physical functioning as well as for the total FIQ and other components. Internal consistency was 0.90 for the overall FIQ. Significant correlations were obtained between the FIQ items, the HAQ and the SF-36.
Conclusions: The Italian FIQ is a reliable and valid instrument for detecting and measuring functional disability and health status in Italian patients with FM.