title: Reliability, validity and factor structure of the GHQ-28 used among elderly Iranians.
abstract: BACKGROUND
  The object of this study was to develop an Iranian version of the General Health Questionnaire-28 (GHQ-28) for use with elderly subjects.
  
  
  METHODS
  The GHQ-28 Farsi version was evaluated for face validity among 204 elderly subjects aged 59 years or older, chosen randomly from residents of Tehran. The Composite International Diagnostic Interview (CIDI) was used to establish a gold standard diagnosis of mental disorders.
  
  
  RESULTS
  The GHQ-28 was an internally consistent measure. Cronbach's alpha, split-half coefficients and test-retest reliability were 0.9, 0.89 and 0.58 respectively. Four factors were extracted using factor analysis: "depression," "psychosocial activity," "anxiety," and "somatic." Using receiver operating curve (ROC) analysis, the optimum cutoff score for the GHQ-28 in this group was 19/20 (sensitivity 0.83, specificity 0.76). Using a loading of 0.6 or greater, a short form of the instrument (GHQ-15) (alpha=0.9) was derived and correlated well with the longer form of the scale (r=0.97). Using ROC analysis, the optimum cutoff score was 10/11 (sensitivity 0.83, specificity 0.69).
  
  
  CONCLUSIONS
  The short and long forms of the GHQ-28 are suitable screening instruments for elderly Iranian residents, particularly those living in urban areas.
authors.affiliation: Tehran Psychiatric Institute, Mental Health Research Center, Iran. kmalakouti@iums.ac.ir
authors.forename: Seyed Kazem
authors.initials: SK
authors.lastname: Malakouti
authors.forename: Paridokht
authors.initials: P
authors.lastname: Fatollahi
authors.forename: Arash
authors.initials: A
authors.lastname: Mirabzadeh
authors.forename: Taher
authors.initials: T
authors.lastname: Zandi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001008:Anxiety Disorders / Q000453:epidemiology; D003863:Depression / Q000453:epidemiology; D005163:Factor Analysis, Statistical; D005260:Female; D006304:Health Status; D006801:Humans; D007492:Iran; D008297:Male; D008403:Mass Screening; D001523:Mental Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000208:ethnology*; D008875:Middle Aged; D011584:Psychology; D012372:ROC Curve; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires