Objective: To assess the relative validity of a semi-quantitative food frequency questionnaire (SQFFQ) against 28 day weighed diet records (WDRs).
Subjects and methods: The SQFFQ was administered to 106 (21 male and 85 female) Japanese dietitians in Aichi Prefecture in autumn, 1996 and four-season consecutive 7 day WDRs were carried out during 1996-1997. We evaluated validity of intakes of 15 foods and 31 macro- and micro-nutrients based on the SQFFQ against those according to 28 day WDRs among 79 Japanese female dietitians.
Results: Mean daily intakes of selected foods and nutrients determined by the SQFFQ were generally equivalent to those measured by 28 day WDRs. Pearson's de-attenuated correlation coefficients (CCs) with log-transformation and energy-adjustment between intakes of selected foods and nutrients quantified by the SQFFQ and 28 day WDRs (minimum-median-maximum) ranged from 0.17 (beverages)-0.52 to 0.74 (rice), and Spearman's rank CCs with energy-adjustment ranged from 0.28 (confectionery)-0.42 to 0.68 (rice). Respective Pearson's CCs for intakes of nutrients were 0.28 (PUFAs)-0.51 to 0.73 (magnesium), and Spearman's rank CCs ranged from 0.23 (n-3 PUFAs)-0.45 to 0.71 (magnesium). Favorably higher agreement for intakes of foods/nutrients was achieved along with lower disagreement.
Conclusions: Satisfactorily higher relative validity was attained in Japanese female dietitians with the SQFFQ. This calibrated questionnaire seems therefore appropriate for administration to Japanese dietitians to clarify associations between diet and health/disease.
Sponsorship: A grant-in-aid from the Ministry of Education, Science, Sports and Culture (06454242).