title: Reproducibility and validity of an FFQ developed for the Korea National Health and Nutrition Examination Survey (KNHANES).
abstract: OBJECTIVE
  We aimed to evaluate the reproducibility and validity of the newly developed FFQ for the Korean National Health and Nutrition Examination Survey (KNHANES) and to estimate the measure's calibration factors.
  
  
  METHODS
  The 109-item FFQ was administered twice, approximately 9 months apart. We also collected four seasonal 3 d dietary records (DR) as a reference method. Correlation coefficients and joint classification were computed to compare intakes of energy, thirteen nutrients and eleven food groups between the two FFQ to evaluate reproducibility. For validity, de-attenuated and energy-adjusted correlation, joint classification and Bland-Altman statistics were calculated for energy and nutrients between the first FFQ and the DR. To calibrate the FFQ, we performed a linear regression analysis in which the DR were the dependent variables and FFQ, age and sex were the independent variables.
  
  
  METHODS
  Seoul metropolitan area, Republic of Korea.
  
  
  METHODS
  A total of 126 adults aged 20-65 years.
  
  
  RESULTS
  The average correlation coefficients measuring reproducibility were 0·54 for nutrients and 0·57 for food groups. The mean correlation coefficient measuring validity was 0·40 for all nutrients between the first FFQ and the DR. On average, 75 % of the participants were classified into the same or adjacent quartiles, while 5 % of the participants were grossly misclassified. The mean energy and nutrient intakes estimated by the calibrated FFQ were similar to the means estimated by the DR.
  
  
  CONCLUSIONS
  The newly developed FFQ for assessing dietary intake in the KNHANES has acceptable reproducibility and modest validity compared with a 12 d DR collected over a 9-month period.
authors.affiliation: 1Department of Food and Nutrition,Seoul National University,Gwanak-gu,Seoul,Republic of Korea.
authors.forename: Dong Woo
authors.initials: DW
authors.lastname: Kim
authors.affiliation: 1Department of Food and Nutrition,Seoul National University,Gwanak-gu,Seoul,Republic of Korea.
authors.forename: Sujin
authors.initials: S
authors.lastname: Song
authors.affiliation: 2Department of Food and Nutrition,Sookmyung Women's University,Yongsan-gu,Seoul,Republic of Korea.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: 3Division of Health and Nutrition Survey,Korea Centers for Disease Control and Prevention,Cheongwon-gun,Chungcheongbuk-do,Republic of Korea.
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Oh
authors.affiliation: 3Division of Health and Nutrition Survey,Korea Centers for Disease Control and Prevention,Cheongwon-gun,Chungcheongbuk-do,Republic of Korea.
authors.forename: Jeeseon
authors.initials: J
authors.lastname: Shim
authors.affiliation: 3Division of Health and Nutrition Survey,Korea Centers for Disease Control and Prevention,Cheongwon-gun,Chungcheongbuk-do,Republic of Korea.
authors.forename: Sanghui
authors.initials: S
authors.lastname: Kweon
authors.affiliation: 1Department of Food and Nutrition,Seoul National University,Gwanak-gu,Seoul,Republic of Korea.
authors.forename: Hee Young
authors.initials: HY
authors.lastname: Paik
authors.affiliation: 4The Graduate School of Public Health and Institute of Health and Environment,Seoul National University,1 Gwanak-ro,Gwanak-gu,Seoul 151-742,Republic of Korea.
authors.forename: Hyojee
authors.initials: H
authors.lastname: Joung
mesh_terms: D000328:Adult; D000368:Aged; D002138:Calibration; D015930:Diet Records; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015203:Reproducibility of Results; D056910:Republic of Korea; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: KNHANES