title: A comparison of a food frequency questionnaire with a 24-hour recall for use in an epidemiological cohort study: results from the biomarker-based Observing Protein and Energy Nutrition (OPEN) study.
abstract: BACKGROUND
  Most large cohort studies have used a food frequency questionnaire (FFQ) for assessing dietary intake. Several biomarker studies, however, have cast doubt on whether the FFQ has sufficient precision to allow detection of moderate but important diet-disease associations. We use data from the Observing Protein and Energy Nutrition (OPEN) study to compare the performance of a FFQ with that of a 24-hour recall (24HR).
  
  
  METHODS
  The OPEN study included 484 healthy volunteer participants (261 men, 223 women) from Montgomery County, Maryland, aged 40-69. Each participant was asked to complete a FFQ and 24HR on two occasions 3 months apart, and a doubly labelled water (DLW) assessment and two 24-hour urine collections during the 2 weeks after the first FFQ and 24HR assessment. For both the FFQ and 24HR and for both men and women, we calculated attenuation factors for absolute energy, absolute protein, and protein density.
  
  
  RESULTS
  For absolute energy and protein, a single FFQ's attenuation factor is 0.04-0.16. Repeat administrations lead to little improvement (0.08-0.19). Attenuation factors for a single 24HR are 0.10-0.20, but four repeats would yield attenuations of 0.20-0.37. For protein density a single FFQ has an attenuation of 0.3-0.4; for a single 24HR the attenuation factor is 0.15-0.25 but would increase to 0.35-0.50 with four repeats.
  
  
  CONCLUSIONS
  Because of severe attenuation, the FFQ cannot be recommended as an instrument for evaluating relations between absolute intake of energy or protein and disease. Although this attenuation is lessened in analyses of energy-adjusted protein, it remains substantial for both FFQ and multiple 24HR. The utility of either of these instruments for detecting important but moderate relative risks (between 1.5 and 2.0), even for energy-adjusted dietary factors, is questionable.
authors.affiliation: Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD 20892, USA. schatzka@mail.nih.gov
authors.forename: Arthur
authors.initials: A
authors.lastname: Schatzkin
authors.forename: Victor
authors.initials: V
authors.lastname: Kipnis
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Carroll
authors.forename: Douglas
authors.initials: D
authors.lastname: Midthune
authors.forename: Amy F
authors.initials: AF
authors.lastname: Subar
authors.forename: Sheila
authors.initials: S
authors.lastname: Bingham
authors.forename: Dale A
authors.initials: DA
authors.lastname: Schoeller
authors.forename: Richard P
authors.initials: RP
authors.lastname: Troiano
authors.forename: Laurence S
authors.initials: LS
authors.lastname: Freedman
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003903:Deuterium; D004034:Diet Surveys; D004044:Dietary Proteins / Q000008:administration & dosage*; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D009584:Nitrogen / Q000652:urine; D010103:Oxygen Isotopes; D010349:Patient Compliance; D013223:Statistics as Topic; D011795:Surveys and Questionnaires
chemical_list: D004044:Dietary Proteins; D010103:Oxygen Isotopes; D003903:Deuterium; D009584:Nitrogen