title: Validity of retrospective diet history: assessing recall of midlife diet using food frequency questionnaire in later life.
abstract: OBJECTIVE
  Limited information exists on the validity of dietary information given by elderly people on their past diet. Here we test the relative validity of a food frequency questionnaire asking older persons about their midlife diet.
  
  
  METHODS
  Retrospective food intake of 56-72-year-old subjects was estimated using a food frequency questionnaire designed for the AGES-Reykjavik Study (AGES-FFQ), an epidemiological study of older individuals. Results were compared with detailed dietary data gathered from the same individuals 18-19 years previously, i.e., in midlife, as part of a national cohort. Spearman correlation and cross-classifications were used to assess the ability of the AGES-FFQ to rank subjects according to their intake.
  
  
  METHODS
  Nationwide, Iceland.
  
  
  METHODS
  Subjects, born 1937-1952 (n=174), who participated in the 1990 Icelandic National Dietary Survey.
  
  
  METHODS
  Dietary intake, estimated by the AGES-FFQ (2008-2009), and dietary history obtained from the 1990 Icelandic National Dietary Survey as a reference method.
  
  
  RESULTS
  The strongest correlation between the AGES-FFQ and the reference method was found for cod liver oil, r=0.53, p<0.001 and r=0.56, p<0.001, for men and women, respectively. For men the corresponding correlation coefficient for milk and dairy products was r=0.43, p<0.001. The correlation coefficients were lower but within a reasonably acceptable range (r=0.26-0.40) for meat, fish and potatoes for both genders, as well as fresh fruits and milk/dairy products for women and whole-wheat bread, oatmeal/muesli and blood/liver-sausage for men. No correlation was found between the AGES-FFQ and the dietary history for rye bread and vegetable consumption. Subjects were categorized into five groups according to level of consumption by the two methods. Cross-classification showed that 16-59% were classified into same group and 43-91% into same or adjacent group, 0-14% were grossly misclassified into opposite groups.
  
  
  CONCLUSIONS
  The AGES-FFQ on midlife diet was found suitable to rank individuals by their intake of several important food groups.
authors.affiliation: Unit for Nutrition Research, University of Iceland and Landspitali-University Hospital, Reykjavik, Iceland.
authors.forename: T
authors.initials: T
authors.lastname: Eysteinsdottir
authors.forename: I
authors.initials: I
authors.lastname: Gunnarsdottir
authors.forename: I
authors.initials: I
authors.lastname: Thorsdottir
authors.forename: T
authors.initials: T
authors.lastname: Harris
authors.forename: L J
authors.initials: LJ
authors.lastname: Launer
authors.forename: V
authors.initials: V
authors.lastname: Gudnason
authors.forename: L
authors.initials: L
authors.lastname: Steingrimsdottir
mesh_terms: D000328:Adult; D000368:Aged; D003060:Cod Liver Oil; D015331:Cohort Studies; D004032:Diet; D015930:Diet Records; D004034:Diet Surveys; D002149:Energy Intake; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D007055:Iceland; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D015203:Reproducibility of Results; D012189:Retrospective Studies; D057566:Self Report; D012737:Sex Factors; D011795:Surveys and Questionnaires / Q000592:standards
chemical_list: D003060:Cod Liver Oil