Relative validity of dietary patterns derived from a self-administered diet history questionnaire using factor analysis among Japanese adults.

Objective: Although dietary pattern approaches derived from dietary assessment questionnaires are widely used, only a few studies in Western countries have reported the validity of this approach. We examined the relative validity of dietary patterns derived from a self-administered diet history questionnaire (DHQ) among Japanese adults. Design: The DHQ, assessing diet during the preceding month, and 4 d dietary records (DR) were collected in each season over one year. To derive dietary patterns, 145 food items in the DHQ and 1259 in the DR were classified into thirtythree predefined food groups, and entered into a factor analysis. Setting: Three areas in Japan; Osaka (urban), Nagano (rural inland) and Tottori (rural coastal). Subjects: A total of ninety-two Japanese women and ninety-two Japanese men aged 31-76 years. Results: We identified three dietary patterns ('healthy', 'Western' and 'Japanese traditional') in women and two ('healthy' and 'Western') in men, which showed a relatively similar direction and magnitude of factor loadings of food groups across the first and mean of four DHQ (DHQ1 and mDHQ, respectively) and 16 d DR. The Pearson correlation coefficients between DHQ1 and 16 d DR for the healthy, Western and Japanese traditional patterns in women were 0·57, 0·36 and 0·44, and for the healthy and Western patterns in men were 0·62 and 0·56, respectively. When mDHQ was examined, the correlation coefficients improved for women (0·45-0·69). Conclusions: Dietary patterns derived from the DHQ could be used for epidemiological studies as surrogates of those derived from DR. [ABSTRACT FROM AUTHOR]