A Brazilian Portuguese version of the Revised Fibromyalgia Impact Questionnaire (FIQR): a validation study

The Fibromyalgia Impact Questionnaire (FIQ) was specifically developed to assess disease severity and functional ability in fibromyalgia patients. In 2009, a revised version of the FIQ was published, the FIQR; this version achieved a better balance among different domains (function, overall impact, symptoms). Here, we present the validity and reliability of the Brazilian version of the Revised Fibromyalgia Impact Questionnaire (FIQR). Female fibromyalgia patients (n = 106) completed an online survey consisting of the Short Form 36 (SF-36) questionnaire, the original FIQ, and the Brazilian Portuguese FIQR, which was translated by a standard method. Validity was established with correlational analyses between the FIQR, FIQ, and SF-36 items. Three domains were established for the FIQR (function, overall impact, symptoms), and their contribution for the SF-36 subscales was also scrutinized. The Brazilian FIQR validation process showed that the questions performed in a very similar way to the original English FIQR. The new questions in the FIQR symptoms domain (memory, balance, tenderness, and environmental sensitivity) revealed a significant impact in fibromyalgia (FM) patients. The Brazilian Portuguese FIQR demonstrated excellent reliability, with a Cronbach's alpha of 0.96. There was a gain on weight of the function domain and a decrease of the symptom domain, leading to a better balance among domains. The FIQR predicted a great number of SF-36 subscales, showing good convergent validity. The Brazilian Portuguese version of the FIQR was validated and found to be a reliable, easy-to-use, and score FM-specific questionnaire that should prove useful in routine clinical practice and FM-related research.