Cross-cultural adaptation and validation of the Impact of Fixed Appliances Measure questionnaire in Brazil.

The aim of this study was to translate and cross-culturally adapt the condition-specific instrument Impact of Fixed Appliances Measure (IFAM), assessing its validity and reliability for use among Brazilian children/adolescents. The IFAM was translated, back-translated, cross-culturally adapted, and pilot-tested. The Brazilian version of the IFAM (B-IFAM) was tested on 161 10-to-18-year-old children/adolescents. Internal consistency was assessed using Cronbach's alpha (alpha) and test-retest reliability by intraclass correlation coefficients (ICC). Construct validity was conducted using Pearson correlation among the overall and subscales of the B-IFAM. Discriminant validity was evaluated by comparisons of B-IFAM's means and SD with children's/adolescents' sex (Student t-test). Internal consistency was 0.89 for overall score and 0.55-0.86 for subscales. ICC for test-retest reliability was 0.81 for overall score and 0.55-0.78 for subscales. The overall score of the B-IFAM presented large correlation coefficients with most subscales (r = 0.52-0.74), supporting construct validity. Discriminant validity demonstrated statistically significant difference in the overall score, aesthetics, and physical impact subscales among female and male children's/adolescents' (p < 0.05). In the conclusion, the B-IFAM overall score and some subscales demonstrated adequate psychometric properties regarding reliability and validity. The study achieved a specific-condition instrument feasible for use on Brazilian children/adolescents who wear fixed orthodontic appliances.