title: Confirmatory factor analysis of the General Health Questionnaire (GHQ-12) in Spanish adolescents.
abstract: OBJECTIVE
  To evaluate the factor structure of the 12-item General Health Questionnaire (GHQ-12) in a population of Spanish adolescents.
  
  
  METHODS
  Cross-sectional study among 4,146 individuals (mean age 16.3 years). The students completed a health questionnaire that included the GHQ-12. A confirmatory factor analysis (CFA) was conducted with four factor structure models. Three of the models were theory-driven: unidimensional, two-dimensional (positive and negative questions), model proposed by Graetz (anxiety and depression, social dysfunction, loss of confidence); and the fourth model was based on our exploratory factor analysis (EFA).
  
  
  RESULTS
  The Cronbach's alpha for internal consistency was 0.82. A three-dimensional structure was identified in the EFA. The first factor included items 1, 2, 5, 6, 7, and 9 of the GHQ-12; the second, items 3, 10, and 11; and the third, items 4, 8, and 12. The three factors together explained 53.7% of the variance. The model with the best fit in the CFA was the three-dimensional model proposed by Graetz, followed by the three-dimensional model derived from the EFA. These two models had acceptable goodness-of-fit indices.
  
  
  CONCLUSIONS
  In an adolescent population from Southern Europe, the GHQ-12 showed high internal consistency. The factor structure that best fitted the data was the Graetz three-dimensional model. However, the high correlations observed between factors suggest that the GHQ-12 should be used as a unidimensional scale, as currently done.
authors: Public Health Centre, Area 10. Consejería de Sanidad de Madrid. C/Francisco Gasco Santillán 2, portal B 2º, Getafe, Spain.
authors: Alicia
authors: A
authors: Padrón
authors: Iñaki
authors: I
authors: Galán
authors: María
authors: M
authors: Durbán
authors: Ana
authors: A
authors: Gandarillas
authors: Fernando
authors: F
authors: Rodríguez-Artalejo
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D005163:Factor Analysis, Statistical; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis*; D015233:Models, Statistical; D011594:Psychometrics / Q000295:instrumentation; D015203:Reproducibility of Results; D013030:Spain; D011795:Surveys and Questionnaires / Q000592:standards*