title: The web-based ASSO-food frequency questionnaire for adolescents: relative and absolute reproducibility assessment.
abstract: BACKGROUND
  A new food frequency questionnaire (FFQ) has been recently developed within the Italian Adolescents and Surveillance System for the Obesity prevention (ASSO) Project; it was found to be appropriate for ranking adolescents in food and nutrient levels of intake. The aim of this study was to assess the relative and absolute reproducibility of the ASSO-FFQ for 24 food groups, energy and 52 nutrients.
  
  
  METHODS
  A test-retest study was performed on two ASSO-FFQs administered one month apart of each other to 185 adolescents, aged 14-17 and attending secondary schools in Palermo (Italy). Wilcoxon test assessed differences in median daily intakes between the two FFQs. Agreement was evaluated by quintiles comparison and weighted kappa. Intraclass Correlation Coefficients (ICC) and Bland-Altman method assessed the relative and absolute reliability respectively.
  
  
  RESULTS
  Significant difference (p < 0.05) in median intakes was found only for bread substitutes, savoury food, water, soft drinks, carbohydrates and sugar. The subjects classified into the same or adjacent quintiles for food groups ranged from 62% (white bread) to 91% (soft drinks); for energy and nutrients from 64% (polyunsaturated fatty acids) to 90% (ethanol). Mean values of weighted kappa were 0.47 and 0.48, respectively for food groups and nutrients. Fair to good ICC values (>0.40) were assessed for thirteen food groups, energy and forty-three nutrients. Limits of Agreement were narrow for almost all food groups and all nutrients.
  
  
  CONCLUSIONS
  The ASSO-FFQ is a reliable instrument for estimating food groups, energy and nutrients intake in adolescents.
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Filippi
authors.forename: Emanuele
authors.initials: E
authors.lastname: Amodio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Napoli
authors.forename: João
authors.initials: J
authors.lastname: Breda
authors.forename: Antonino
authors.initials: A
authors.lastname: Bianco
authors.forename: Monèm
authors.initials: M
authors.lastname: Jemni
authors.forename: Laura
authors.initials: L
authors.lastname: Censi
authors.forename: Caterina
authors.initials: C
authors.lastname: Mammina
authors.affiliation: Department of Sciences for Health Promotion and Mother Child Care "G, D'Alessandro", University of Palermo Via Del Vespro 133, 90127 Palermo, Italy. tabacc0068i.garden@libero.it.
authors.forename: Garden
authors.initials: G
authors.lastname: Tabacchi
mesh_terms: D000293:Adolescent; D000434:Alcoholic Beverages; D001939:Bread; D002253:Carbonated Beverages; D004032:Diet; D015930:Diet Records; D002149:Energy Intake; D005260:Female; D005502:Food; D006801:Humans; D020407:Internet; D007558:Italy; D008297:Male; D009765:Obesity / Q000517:prevention & control; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires