title: Construction and evaluation of a self-contained index for assessment of diet quality.
abstract: OBJECTIVE
  To construct and validate a self-contained index for the evaluation of a health-promoting diet in adults.
  
  
  METHODS
  Participants (n = 103) were healthy volunteer adults aged 20 to 64 years. A food consumption questionnaire containing 55 questions was formulated and evaluated against seven-day food records. Key questions best reflecting the health-promoting diet, defined in nutrition recommendations, were identified by correlation and ROC analyses in comparison to calculated food and nutrient intakes from the food records. A shorter questionnaire was scored to compile an Index of Diet Quality (IDQ).
  
  
  RESULTS
  Based on ROC analyses 18 questions were sufficient to describe the health-promoting diet and comprised the index. IDQ had a sensitivity of 67% and a specificity of 71%. The IDQ score reflected dietary intake, shown as statistically significant correlations between higher IDQ scores and higher intakes of protein (r = 0.35), fibre (r = 0.42), calcium (r = 0.39), iron (r = 0.31), vitamin C (r = 0.31) and a higher ratio of unsaturated to saturated fatty acids (r = 0.23) and a lower intake of saturated fatty acids (r = -0.22) and saccharose (r = -0.25).
  
  
  CONCLUSIONS
  IDQ reflects dietary intake of key foods and nutrients associated with health and depicts adherence to dietary recommendations. It is applicable in nutritional studies where diet in its entirety is of interest and also in large-scale studies, being fast in execution with analysis free of complex calculations.
authors.affiliation: Turku Institute for Child and Youth Research, Turku, Finland. johanna.leppala@utu.fi
authors.forename: Johanna
authors.initials: J
authors.lastname: Leppälä
authors.forename: Hanna
authors.initials: H
authors.lastname: Lagström
authors.forename: Anne
authors.initials: A
authors.lastname: Kaljonen
authors.forename: Kirsi
authors.initials: K
authors.lastname: Laitinen
mesh_terms: D000328:Adult; D000368:Aged; D004032:Diet / Q000592:standards*; D004034:Diet Surveys; D004045:Dietary Services; D002149:Energy Intake; D005260:Female; D005387:Finland; D019983:Guideline Adherence; D006293:Health Promotion; D006801:Humans; D008297:Male; D008875:Middle Aged; D018673:Nutrition Policy; D057566:Self Report; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires / Q000592:standards*