title: Validation of a food-frequency questionnaire for cohort studies in rural Japan.
abstract: OBJECTIVE
  To examine the validity and reproducibility of a self-administered food-frequency questionnaire (FFQ) used for two cohort studies in Japan.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Two rural towns in the Miyagi Prefecture, in north-eastern Japan.
  
  
  METHODS
  Fifty-five men and 58 women.
  
  
  RESULTS
  A 40-item FFQ was administered twice, 1 year apart. In the mean time, four 3-day diet records (DRs) were collected in four seasons within the year. We calculated daily consumption of total energy and 15 nutrients, 40 food items and nine food groups from the FFQs and the DRs. We computed Spearman correlation coefficients between the FFQs and the DRs. With adjustment for age, total energy and deattenuation for measurement error with the DRs, the correlation coefficients for nutrient intakes ranged from 0.25 to 0.58 in men and from 0.30 to 0.69 in women, with median of 0.43 and 0.43, respectively. Median (range) of the correlation coefficients was 0.35 (-0.30 to 0.72) in men and 0.34 (-0.06 to 0.75) in women for food items and 0.60 (-0.10 to 0.76) and 0.51 (0.28-0.70) for food groups, respectively. Median (range) of the correlation coefficients for the two FFQs administered 1 year apart was 0.49 (0.31-0.71) in men and 0.50 (0.40-0.64) in women for nutrients, 0.43 (0.14-0.76) and 0.45 (0.06-0.74) respectively for food items, and 0.50 (0.30-0.70) and 0.57 (0.39-0.66) respectively for food groups. Relatively higher agreement percentages for intakes of nutrients and food groups with high validity were obtained together with lower complete disagreement percentages.
  
  
  CONCLUSIONS
  The FFQ has a high reproducibility and a reasonably good validity, and is useful in assessing the usual intakes of nutrients, foods and food groups among a rural Japanese population.
authors.affiliation: Division of Epidemiology, Department of Public Health, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Ogawa
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Tsubono
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Nishino
authors.forename: Yoko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Takao
authors.initials: T
authors.lastname: Watanabe
authors.forename: Haruo
authors.initials: H
authors.lastname: Nakatsuka
authors.forename: Nobuko
authors.initials: N
authors.lastname: Takahashi
authors.forename: Mieko
authors.initials: M
authors.lastname: Kawamura
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tsuji
authors.forename: Shigeru
authors.initials: S
authors.lastname: Hisamichi
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015930:Diet Records; D004034:Diet Surveys; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012424:Rural Population; D012621:Seasons; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires / Q000592:standards*