title: Validation of an instrument to evaluate quality of life in the aging population: WHOQOL-AGE.
abstract: BACKGROUND
  There is a need for short, specific instruments that assess quality of life (QOL) adequately in the older adult population. The aims of the present study were to obtain evidence on the validity of the inferences that could be drawn from an instrument to measure QOL in the aging population (people 50+ years old), and to test its psychometric properties.
  
  
  METHODS
  The instrument, WHOQOL-AGE, comprised 13 positive items, assessed on a five-point rating scale, and was administered to nationally representative samples (n = 9987) from Finland, Poland, and Spain. Cronbach's alpha was employed to assess internal consistency reliability, whereas the validity of the questionnaire was assessed by means of factor analysis, graded response model, Pearson's correlation coefficient and unpaired t-test. Normative values were calculated across countries and for different age groups.
  
  
  RESULTS
  The satisfactory goodness-of-fit indices confirmed that the factorial structure of WHOQOL-AGE comprises two first-order factors. Cronbach's alpha was 0.88 for factor 1, and 0.84 for factor 2. Evidence supporting a global score was found with a second-order factor model, according to the goodness-of-fit indices: CFI = 0.93, TLI = 0.91, RMSEA = 0.073. Convergent validity was estimated at r = 0.75 and adequate discriminant validity was also found. Significant differences were found between healthy individuals (74.19 ± 13.21) and individuals with at least one chronic condition (64.29 ± 16.29), supporting adequate known-groups validity.
  
  
  CONCLUSIONS
  WHOQOL-AGE has shown good psychometric properties in Finland, Poland, and Spain. Therefore, considerable support is provided to using the WHOQOL-AGE to measure QOL in older adults in these countries, and to compare the QOL of older and younger adults.
authors.forename: Francisco Félix
authors.initials: FF
authors.lastname: Caballero
authors.forename: Marta
authors.initials: M
authors.lastname: Miret
authors.forename: Mick
authors.initials: M
authors.lastname: Power
authors.forename: Somnath
authors.initials: S
authors.lastname: Chatterji
authors.forename: Beata
authors.initials: B
authors.lastname: Tobiasz-Adamczyk
authors.forename: Seppo
authors.initials: S
authors.lastname: Koskinen
authors.forename: Matilde
authors.initials: M
authors.lastname: Leonardi
authors.forename: Beatriz
authors.initials: B
authors.lastname: Olaya
authors.forename: Josep Maria
authors.initials: JM
authors.lastname: Haro
authors.affiliation: Department of Psychiatry, Universidad Autónoma de Madrid, Madrid, Spain. joseluis.ayuso@uam.es.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Ayuso-Mateos
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D005060:Europe; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult