Agreement between interview data and a self-administered questionnaire on dietary supplement use

The effectiveness of an open-ended questionnaire on dietary supplement intake is analyzed. The questionnaire had a sensitivity of 65.9%, specificity of 98.5% and kappa, a measure of agreement, of 0.69%. Women users of not less than three supplements, prolonged supplement users and older age groups exhibited a good degree of recall. Specific supplement intake recall was 77.8% for garlic preparations and 11.8% for other supplements.