Validity of a Dietary Questionnaire Assessed by Comparison With Multiple Weighed Dietary Records or 24-Hour Recalls

Abstract

The authors evaluated the validity of a 152-item semiquantitative food frequency questionnaire (SFFQ) by comparing it with two 7-day dietary records (7DDRs) or up to 4 automated self-administered 24-hour recalls (ASA24s) over a 1-year period in the women's Lifestyle Validation Study (2010-2012), conducted among subgroups of the Nurses' Health Studies. Intakes of energy and 44 nutrients were assessed using the 3 methods among 632 US women. Compared with the 7DDRs, SFFQ responses tended to underestimate sodium intake but overestimate intakes of energy, macronutrients, and several nutrients in fruits and vegetables, such as carotenoids. Spearman correlation coefficients between energy-adjusted intakes from 7DDRs and the SFFQ completed at the end of the data-collection period ranged from 0.36 for lauric acid to 0.77 for alcohol (mean r = 0.53). Correlations of the end-period SFFQ were weaker when ASA24s were used as the comparison method (mean r = 0.43). After adjustment for within-person variation in the comparison method, the correlations of the final SFFQ were similar with 7DDRs (mean r = 0.63) and ASA24s (mean r = 0.62). These data indicate that this SFFQ provided reasonably valid estimates for intakes of a wide variety of dietary variables and that use of multiple 24-hour recalls or 7DDRs as a comparison method provided similar conclusions if day-to-day variation was taken into account.

Keywords: 7-day dietary records; automated self-administered 24-hour recall; nutrient validation; reproducibility; semiquantitative food frequency questionnaire.

Figure 1.

Timeline of the dietary assessment activity in the Lifestyle Validation Study, embedded in the Nurses’ Health Study and Nurses’ Health Study II, United States, 2010–2012. This figure shows the timeline for group 1 participants. Groups 2 and 4 were assigned similar data collection timeline as group 1, except groups 2 and 4 participants were asked to complete the 7-day dietary record (7DDR) in phases II and IV instead. Group 3 went through the same data collection timeline as group 1. Within the same phase, 7DDRs and automated self-administered 24-hour dietary recalls (ASA24s) were completed 2–5 weeks apart (to avoid artificially high correlations). For groups 1 and 3, the ASA24 was completed first, followed by the 7DDR in phase I, but this order was reversed in phase III. For groups 2 and 4, the 7DDR was completed first followed by the ASA24 in phase II, but this order was reversed in phase IV. Additionally, groups 1 and 3 completed the web-based version of the food frequency questionnaire (WebFFQ), which was enhanced by the use of branched questions, approximately 2 weeks before completion of the paper semiquantitative food frequency questionnaire (SFFQ) (the final SFFQ, conducted at the end of the follow-up period), and groups 2 and 4 completed it approximately 2 weeks after completion of the final SFFQ. To minimize alteration in eating behavior, the participants were not told in advance the day that they would be asked to complete the ASA24; days were randomly selected and may or may not have included a weekend day.