Factorial validity and reliability of the General Health Questionnaire (GHQ-12) in the Brazilian physician population.

The 12-item General Health Questionnaire (GHQ-12) is a widely used screening instrument. One- and two-factor structures have been identified in some countries. In Brazil, the best factor structure is still unclear. This study aimed at knowing its factorial validity and reliability, and testing the one-factor and two-factor models. The participants were 7,512 Brazilian physicians. They answered the GHQ-12 and demographic questions. Unrotated (one-factor) and rotated (two-factor) structures of the GHQ-12 were extracted by principal component analysis. Confirmatory factor analyses (ML) were used to compare the one- and two-factor solutions. The two-factor model fitted the data better than the one-factor one. Those two factors were depression and social dysfunction, and they showed themselves to be directly correlated to one another. They also showed adequate reliability coefficients. The two-factor model is remarkably adequate, showing better fit indices, although it is acceptable to admit a common factor, which could be defined as psychological distress.