title: Reproducibility of a food frequency questionnaire in koreans.
abstract: OBJECTIVE
  The present study was conducted to report upon the reproducibility of a 98-item food frequency questionnaire among Koreans.
  
  
  METHODS
  The study subjects were recruited from among those who visited for a regular health check-up at the health centers from Samsung Hospital and Hallym University Hospital.
  
  
  METHODS
  The FFQ was administered first in April to June of 2002 to 145 Korean adults aged 40 and over residing in Seoul and its vicinity and was then re-administered to 126 three months later between July and September of 2002 (FFQ 1 and FFQ 2).
  
  
  METHODS
  Reproducibility was evaluated using the Pearson correlation coefficients of log-e and the calorie-adjusted nutrient score. Weighted kappa (k) statistics with 95% confidence limits were calculated to assess the chance adjusted level of agreement between the FFQ 1 and the FFQ 2. The proportions of correctly categorized subjects in the same or adjacent quintiles were calculated.
  
  
  RESULTS
  The average intake in FFQ 1 was no more than 12 percent different from the average intake in FFQ 2. Correlations varied between 0.47 for sodium and 0.72 for vitamin C. All k values exceeded 0.5 except that of fiber. The average k for all nutrients was 0.67. The percentage agreement varied from 62% for energy and potassium to 82% for vitamin B(2) and cholesterol. The average of the agreement was 72%.
  
  
  CONCLUSIONS
  The results of this study verify that it is possible to use tailored, relatively simple, but comprehensive, self-administered food frequency questionnaires to study nutrient consumption in large-scale epidemiological studies.
mesh_terms: D000328:Adult; D000368:Aged; D004435:Eating; D005260:Female; D006801:Humans; D007723:Korea; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires