Factor Structure, Invariance Analysis and Social Distribution of the Patient Health Questionnaire-9 (PHQ-9)

This research examined the factor structure of the Patient Health Questionnaire-9 (PHQ-9) with a non clinical Brazilian population through exploratory (AFE) and confirmatory (AFC) factor analysis and model invariance. The social distribution of the screening diagnosis for depressive symptoms was also assessed.The complete sample consisted of 4958 adults, which was split into two groups. The first group (n=1000) was used for the EFA and the second group (n=3958) for the CFA. The EFA indicated a single factor structure, which explained 78.5% of variance. The CFA attested to the unidimensionality, with satisfactory fit indices and reliability indicators. The model was invariant in relation to the investigated variables at all measured levels. Finally, the variables sex and school grade were also significant predictors of depressive symptoms. In conclusion, our findings support the utility of the PHQ-9 and it is recommended for usage in research and intervention with the Brazilian population.