Brazilian Portuguese version of the Revised Fibromyalgia Impact Questionnaire (FIQR-Br): cross-cultural validation, reliability, and construct and structural validation.

Purpose: This study aimed to culturally adapt and validate the Revised Fibromyalgia Impact Questionnaire (FIQR) to Brazilian Portuguese, by the use of analysis of internal consistency, reliability, and construct and structural validity. Method: A total of 100 female patients with fibromyalgia participated in the validation process of the Brazilian Portuguese version of the FIQR (FIQR-Br). The intraclass correlation coefficient (ICC) was used for statistical analysis of reliability (test-retest), Cronbach's alpha for internal consistency, Pearson's rank correlation for construct validity, and confirmatory factor analysis (CFA) for structural validity. Results: It was verified excellent levels of reliability, with ICC greater than 0.75 for all questions and domains of the FIQR-Br. For internal consistency, alpha values greater than 0.70 for the items and domains of the questionnaire were observed. Moderate (0.40<r<0.70) and strong (r>0.70) correlations were observed for the scores of domains and total score between the FIQR-Br and FIQ-Br. The structure of the three domains of the FIQR-Br was confirmed by CFA. Conclusions: The results of this study suggest that that the FIQR-Br is a reliable and valid instrument for assessing fibromyalgia-related impact, and supports its use in clinical settings and research. The structure of the three domains of the FIQR-Br was also confirmed. [ABSTRACT FROM AUTHOR]