Assessment of the factor structure and reliability of the Portuguese version of the General Health Questionnaire-28 among adults

The General Health Questionnaire (GHQ, Goldberg & Hillier, 1979 , Psychological Medicine, 9, 139-145) is a self-administered questionnaire used to measure non-psychotic psychiatric disorders. There is a study using a Portuguese version of this questionnaire (n = 60) including a group of inpatients with infectious diseases (Ribeiro & Antunes, 2003 , Revista Portuguesa de Psicossomática, 5(1), 37-45), but there are no larger studies in non-clinical Portuguese population.

The primary aim of the study was to confirm the psychometric properties of the Portuguese version of the GHQ-28 among 171 Portuguese adults in non-clinical settings.

The Portuguese version of the GHQ-28 was administered to 171 adult subjects of Portuguese general population.

The Portuguese version of the GHQ-28 has an internally consistent measure Cronbach's α 0.922 for the GHQ-28 total scale. For the subscale somatic symptoms Cronbach's α was 0.825; for the subscale Anxiety/ Insomnia, Cronbach's α was 0.873; for the subscale Social dysfunction Cronbach's α was 0.873 and for the subscale Severe Depression was 0.838. Four factors were extracted using factor analysis: somatic symptoms (items 1-7); anxiety/insomnia (items 8-14); psychosocial dysfunction (items 15-21); and severe depression (items 22-28).

The findings suggest that the GHQ-28 is a suitable screening instrument for adult Portuguese population in non-clinical settings.