Validity of the food frequency questionnaire for adults in nutritional epidemiological studies: A systematic review and meta-analysis

As the most widely used tool for assessing dietary intake, the validity of food frequency questionnaires (FFQs) should be evaluated before application. A comprehensive search of the PubMed and Web of Science databases was conducted for publications from January 2000 to April 1, 2020. Pooled estimates were calculated for correlation coefficients and mean differences for energy and 61 nutrients between FFQs and standard methods. The literature search identified 130 articles that included 21,494 participants. Subgroup analyses according to the number of administrations of the reference method, sample size, administration methods, FFQ items, reference periods, quality of the studies, gender, and regions were also performed. We conducted a meta-analysis by summarizing the available evidence to comprehensively assess the validity of FFQs stratified by the reference method type (24-hour recall (24HRs) and food records (FRs). We also performed subgroup analyses to examine the impact on the final summary estimates. After a meta-analysis of the FFQs' validity correlation coefficients of the included studies, this study showed that the range (median) of the validity coefficients of the 24HRs as reference methods was 0.220-0.770 (0.416), and for the FRs, it was 0.173-0.735 (0.373), which indicated that FFQs were suitable to assess the overall dietary intake in nutritional epidemiological studies. The results of the subgroup analysis showed that the number of administrations of the reference method, administration mode, number of items, reference periods, sample size, and gender mainly affected the validity correlation of FFQs.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.1966737 .