Perceived subject outcomes and impact on health-related quality of life associated with diet using the new Food Benefits Assessment (FBA) questionnaire: development and psychometric validation.
ABSTRACT To assess the perceived outcomes associated with diet/food intake in the general adult population.
The Food Benefits Assessment (FBA) questionnaire was developed from subjects' verbatim transcripts (n 18) and after comprehension tests (n 5). Normal-weight (n 130) and overweight (n 67) subjects then completed the final questionnaire twice, 7 d apart. Psychometric properties were assessed, including construct validity by principal components analysis (PCA), concurrent validity (Spearman coefficient) with the Short Form-36 scale (SF-36), known-group validity by comparing FBA dimension scores according to lifestyle and clinical variables, internal consistency reliability (Cronbach's alpha) and test-retest reproducibility in stable subjects over 1 week (intraclass correlation coefficient, ICC).
PCA and Multitrait analysis confirmed the final version of the FBA comprising forty-one items split into seven dimensions (vitality; digestive comfort; physical appearance; well-being; snacking; disease prevention; aesthetics). All dimensions displayed good item convergent validity (0.44 to 0.80), good concurrent validity (highest correlation between well-being dimension of FBA and mental health scale of SF-36, r=0.83) and good known-group validity and reproducibility (ICC >or= 0.76); internal consistency reliability was good to excellent (Cronbach's alpha=0.79 to 0.91).
The FBA is the first valid and reliable questionnaire that allows the assessment of diet effects and impact as perceived by subjects. It is a good candidate in the nutrition field for further use in specific population settings and with a particular food or daily diet. Linguistically validated English (UK and US) and German versions of the questionnaire are available.