title: Reporting accuracy of packed lunch consumption among Danish 11-year-olds differ by gender.
abstract: BACKGROUND
  Packed lunch is the dominant lunch format in many countries including Denmark. School lunch is consumed unsupervised, and self-reported recalls are appropriate in the school setting. However, little is known about the accuracy of recalls in relation to packed lunch.
  
  
  OBJECTIVE
  To assess the qualitative recall accuracy of self-reported consumption of packed lunch among Danish 11-year-old children in relation to gender and dietary assessment method.
  
  
  METHODS
  A cross-sectional dietary recall study of packed lunch consumption. Digital images (DIs) served as an objective reference method to determine food items consumed. Recalls were collected with a lunch recall questionnaire (LRQ) comprising an open-ended recall (OE-Q) and a pre-coded food group prompted recall (PC-Q). Individual interviews (INTs) were conducted successively. The number of food items was identified and accuracy was calculated as match rates (% identified by DIs and reported correctly) and intrusion rates (% not identified by DIs but reported) were determined.
  
  
  METHODS
  Three Danish public schools from Copenhagen. A total of 114 Danish 11-year-old children, mean (SE) age=11.1 (0.03), and body mass index=18.2 (0.26).
  
  
  RESULTS
  The reference (DIs) showed that girls consumed a higher number of food items than boys [mean (SE) 5.4 (0.25) vs. 4.6 (0.29) items (p=0.05)]. The number of food items recalled differed between genders with OE-Q recalls (p=0.005) only. Girls' interview recalls were more accurate than boys' with higher match rates (p=0.04) and lower intrusion rates (p=0.05). Match rates ranged from 67-90% and intrusion rates ranged from 13-39% with little differences between girls and boys using the OE-Q and PC-Q methods.
  
  
  CONCLUSIONS
  Dietary recall validation studies should not only consider match rates as an account of accuracy. Intrusions contribute to over-reporting in non-validation studies, and future studies should address recall accuracy and inaccuracies in relation to gender and recall method.
authors.affiliation: Division of Nutrition, National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Nina
authors.initials: N
authors.lastname: Lyng
authors.forename: Sisse
authors.initials: S
authors.lastname: Fagt
authors.forename: Michael
authors.initials: M
authors.lastname: Davidsen
authors.forename: Camilla
authors.initials: C
authors.lastname: Hoppe
authors.forename: Bjørn
authors.initials: B
authors.lastname: Holstein
authors.forename: Inge
authors.initials: I
authors.lastname: Tetens
keywords: recall accuracy; school lunch; self-reported intake