Adaptation and validation of a questionnaire for assessing practices toward salt and sodium in Brazilian adolescents and young adults

Objective This study aimed to adapt and validate an online instrument assessing Brazilian adolescents' and young adults' practices regarding salt and sodium. Methods Based on a developed questionnaire for adults, nine experts evaluated new items, generating item and scale-level content validity indexes, with acceptable cut-off point of 0.8. Face validity (n=20) and reliability analysis (kappa) (n=30) were assessed. Items were excluded if kappa <0.5. Exploratory factor analysis was used to determine the construct validity. Items with factor loadings <|0.3|were considered non-significant and excluded. Cronbach's alpha was calculated to assess internal structure, using data collected from a convenience sample (n=345). Coefficient values >= 0.7 were considered satisfactory. Generated solutions were analyzed from theoretical and statistical significance perspectives to achieve the best model. Results Item-level content validity index (0.78-1), scale-level content validity index (0.96-0.99) and kappa values (97% of items with kappa >0.5) demonstrated that items are adequate for application. The final model in the exploratory factor analysis sufficiently explained data variance with good internal structure (Cronbach's alpha=0.79; 95% CI 0.75-0.82). The valid questionnaire has two dimensions - one related to behavioral practices (8 items), and another to dietary markers (13 items). Conclusion This instrument is ready to be applied and easily reproduced, contributing to assessing practices toward salt and sodium in Brazilian youngsters.