Comparison of an Australian food-frequency questionnaire with diet records: implications for nutrition surveillance

Objectives: To compare a widely used Australian food-frequency questionnaire (FFQ) with diet records and consider the results in relation to its use in nutrition surveillance. Design: Inter-method reliability study. Setting: A randomised trial in subjects with past asbestos exposure. Subjects: Seventy-two adults living in Western Australia. Methods: A semi-quantitative FFQ developed by the Commonwealth Scientific Industrial Research Organisation in South Australia was administered after the completion of four 7-day diet records (DRs). Results: Mean agreement between methods was not significantly different from 100% for many nutrients, but the limits of agreement indicated that, at the individual level, the FFQ over- or underestimated the DR by at least 50%. Mean agreement between methods decreased significantly with increasing intakes for the majority of nutrients. Pearson's correlation coefficients were less informative indicators of agreement compared with the limits of agreement. Conclusions: These results indicate poor agreement between the FFQ and DR when estimating absolute intakes. Therefore, comparing intakes collected using this FFQ with specific cut-off points such as Recommended Dietary Intakes for nutrition surveillance may lead to seriously flawed conclusions about population intakes.