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.

OBJECTIVE

To assess the perceived outcomes associated with diet/food intake in the general adult population.

DESIGN AND SUBJECTS

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).

RESULTS

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).

CONCLUSION

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.