Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Oct 7, 2023
Date Accepted: Mar 9, 2024
Relative validity of a digital food frequency questionnaire assessing adherence to the Norwegian food based dietary guidelines and other national lifestyle recommendations
ABSTRACT
Background:
Valid assessments tools are needed when investigating adherence to national dietary and lifestyle guidelines
Objective:
We investigated the relative validity of the new digital food frequency questionnaire, the DIGIKOST-FFQ, against 7-days weighed food records and activity sensors
Methods:
Seventy-seven subjects were included in the validation study and completed the DIGIKOST-FFQ and the weighted food record, of these 56 (73%) also used the activity sensors. The DIGIKOST-FFQ estimate intakes of whole foods according to the Norwegian food based dietary guidelines (FBDG) in addition to lifestyle factors
Results:
At group level, the DIGIKOST-FFQ showed good validity in estimating intakes according to the Norwegian FBDG. The median differences were small and well below portion sizes for all foods, except “water” (median difference: 230 g). The DIGIKOST-FFQ was able to rank individual intakes for all foods (r=0.3-0.7). However, ranking estimates of vegetable intakes should be interpreted with caution. Between 69-88 % of the participants were classified into the same or adjacent quartile for all foods, and between 71-82% for different activity intensities. The Bland Altman plots showed acceptable agreements between DIGIKOST-FFQ and the reference methods. Absolute amount of time in “moderate-to-vigorous intensity” was underestimated with the DIGIKOST-FFQ. However, estimated time in “moderate-to-vigorous intensity” and “vigorous intensity” and “sedentary time” showed acceptable correlations and good agreement between the methods. The DIGIKOST-FFQ was able to identify adherences to the Norwegian FBDG and physical activity.
Conclusions:
The DIGIKOST-FFQ gave valid estimates of dietary intakes and able to identify individuals with different degree of adherence to the Norwegian FBDG and physical activity recommendations. We observed good agreement between the methods in estimating dietary intakes and time in physical activity (“moderate-to-vigorous intensity”), “sedentary time” and “sleep”. Clinical Trial: The Data Protection Services (Sikt) has approved the DIGIKOST-protocol and the informed consent (ref. no. 277679).
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