title: Reproducibility and validity of dietary patterns assessed by a food frequency questionnaire used in the 5-year follow-up survey of the Japan Public Health Center-Based Prospective Study.
abstract: BACKGROUND
  Analysis of dietary pattern is increasingly popular in nutritional epidemiology. However, few studies have examined the validity and reproducibility of dietary patterns. We assessed the reproducibility and validity of dietary patterns identified by a food frequency questionnaire (FFQ) used in the 5-year follow-up survey of the Japan Public Health Center-Based Prospective Study (JPHC Study).
  
  
  METHODS
  The participants were a subsample (244 men and 254 women) from the JPHC Study. Principal component analysis was used to identify dietary patterns from 28- or 14-day dietary records and 2 FFQs. To assess reproducibility and validity, we calculated Spearman correlation coefficients between dietary pattern scores derived from FFQs separated by a 1-year interval, and between dietary pattern scores derived from dietary records and those derived from a FFQ completed after the dietary records, respectively.
  
  
  RESULTS
  We identified 3 Japanese dietary patterns from the dietary records and 2 FFQs: prudent, westernized, and traditional. Regarding reproducibility, Spearman correlation coefficients between the 2 FFQs ranged from 0.55 for the westernized Japanese pattern in men and the prudent Japanese pattern in women to 0.77 for the traditional Japanese pattern in men. Regarding validity, the corresponding values between dietary records and the FFQ ranged from 0.32 for the westernized Japanese pattern in men to 0.63 for the traditional Japanese pattern in women.
  
  
  CONCLUSIONS
  Acceptable reproducibility and validity was shown by the 3 dietary patterns identified by principal component analysis based on the FFQ used in the 5-year follow-up survey of the JPHC Study.
authors.affiliation: Department of Epidemiology and Prevention, International Clinical Research Center, National Center for Global Health and Medicine, Tokyo, Japan. nanri@ri.ncgm.go.jp
authors.forename: Akiko
authors.initials: A
authors.lastname: Nanri
authors.forename: Taichi
authors.initials: T
authors.lastname: Shimazu
authors.forename: Junko
authors.initials: J
authors.lastname: Ishihara
authors.forename: Ribeka
authors.initials: R
authors.lastname: Takachi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mizoue
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003625:Data Collection / Q000379:methods; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009752:Nutritional Status; D011795:Surveys and Questionnaires / Q000592:standards*