Factorial validity and reliability of the General Health Questionnaire (GHQ-12) in the Brazilian physician population Questionário de Saúde Geral (QSG-12) na população médica brasileira: evidências de validade fatorial e consistência interna

The 12-item General Health Questionnaire (GHQ12) is a widely used screening instrument. Oneand 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 oneand 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. Mental Health; Physicians; Questionnaire Introduction There has been a considerable increase in the number of people reporting mental symptoms (such as depression or anxiety) that could be confused with organic problems, and therefore be treated erroneously. Although there are diagnostic tools based on the Diagnostic and Statistical Manual of Mental Disorders 1 for instance, the defined criteria for such diagnoses are the presence of symptoms, its continued duration, and the corresponding deficit to psychical functioning. Despite the heuristic and practical nature of these classifications, they take into account the patient’s behaviors and his or her complaints. Such information is often unreliable and diffuse. There is thus a clear need for counting with available objective measures to assess exclusively current mental health symptoms 2,3. The General Health Questionnaire (GHQ) was developed by Goldberg in the 1970s to achieve this goal 4. The original GHQ is composed of 60 items. However, different shortened versions of this instrument are currently available, according to the number of items (e.g., 30, 28, and 12). The GHQ-12, i.e. the 12-item version, due to its brevity, has probably been the most popular. Searching in Google Scholar (http://scholar.google.com. br/scholar?q=ghq-12&hl-pt-BR&lr=, accessed on 05/Jul/2008), and introducing GHQ-12 as a keyword, 4,410 papers were identified. This version is used in many countries and languages 3,5,6,7,8,9. ARTIGO ARTICLE Gouveia VV et al. 1440 Cad. Saúde Pública, Rio de Janeiro, 26(7):1439-1445, jul, 2010 This instrument asks whether the respondent has experienced a particular symptom or behavior recently. Each item is rated on a four-point scale (less than usual, no more than usual, rather more than usual, or much more than usual), using one of two most common scoring methods: dichotomous (0-0-1-1) or Likert type (0-1-2-3). Considering the GHQ-12 to be a brief, simple and easy to complete instrument, and the fact that its application in research settings as a screening tool is well documented 10,11, we decided to check its psychometric properties in a sample of Brazilian physicians. In spite of evidences of validity and reliability of this measure in this cultural milieu 12,13,14, most of them are of an exploratory nature, considering only one state. Moreover, there is not a consensus about the number of factors to extract in the GHQ-12 in Brazil. For instance, Sarriera et al. 13 identified three factors in Rio Grande do Sul, using Principal Components analysis (varimax rotation), and Borges & Argolo 12, in Rio Grande do Norte, found two factors when using Principal Axis Factoring (oblimin rotation). On the other hand, at least in other countries, some researchers often have compared two-factor and one-factor models by confirmatory factor analysis, concluding that the former has a more adequate fit 2,6,15. Nevertheless, one and three-factor models are also compared 2,16,17. Usually, the two-factor solution (depression and social dysfunction) accounts for between 45.3 and 56.5 per cent of the total variance 3,7, presenting an internal consistency that is close to 0.80 12,13. Gouveia et al. 18 tested three factor models (1-, 2-, and 3-factors) by confirmatory factor analyses. They concluded that the most adequate model was the two-factor one, measuring depression and anxiety (social dysfunction), which showed reasonable Cronbach’s alpha coefficients (0.81 and 0.66, respectively). However, their sample was specific to João Pessoa, and considered a medium sized city in the Northeast of Brazil. Oliveira 19, in this same city, took into account a sample of 246 health professionals, including 98 psychologists, 81 physicians and 67 nurses, all of whom answered the GHQ-12. She performed only exploratory factor analysis, without comparing different factor models for this measure. Two factors were observed, explaining 51.5% of the total variance, with alphas of 0.83 (psychological distress) and 0.76 (lack of self-efficacy). There is no information about the fitness of this model to data. These considerations motivated the current study. Its objectives were, therefore, three-fold. Responding to the recommendation to consider a large sample 2, it aimed at (1) knowing the factor structure underlying the 12-item of the GHQ by performing an exploratory factor analysis; (2) testing the two most common factor models to explain the data obtained by this measure, as discussed in the literature (oneand two-factor models); and (3) knowing evidences of its homogeneity and reliability. In sum, this study searched evidences of factorial validity and reliability of the GHQ-12 in a large physician sample from all 26 Brazilian states and Federal District. Physicians demand mental health attention because they are a professional group often working in stressing labor context, and experiencing many mental illness symptoms 19,20.