Examining the factor structure and discriminant validity of the 12-item General Health Questionnaire (GHQ-12) among Spanish postpartum women.

In this study, the authors tested alternative factor models of the 12-item General Health Questionnaire (GHQ-12) in a sample of Spanish postpartum women, using confirmatory factor analysis. The authors report the results of modeling three different methods for scoring the GHQ-12 using estimation methods recommended for categorical and binary data. A discriminant function analysis was also performed to test the utility of a multiple factor model. A two-phase cross-sectional study was designed: (a) 1,453 women visiting at 6 weeks postpartum completed the GHQ-12 and the Edinburgh Postnatal Depression Scale questionnaire and (b) based on the Edinburgh Postnatal Depression Scale outcomes, participants were stratified and randomly selected within each stratum for clinical evaluation. Using the Likert-type scoring approach, Hankins's one-factor model with "method effects" obtained the best fit. In addition, Graetz's three-factor model provided little discrimination between diagnostic groups, the factors being highly correlated. These results support the presence of only one latent factor in the GHQ-12.