Validation of the subscales of the Edinburgh Postnatal Depression Scale in a sample of women with unsettled infants

Background: The Edinburgh Postnatal Depression Scale (EPDS) was developed as a uni-dimensional measure of depression, however there is evidence that it also measures anxiety. This study examined the factor structure of the EPDS and validity of the identified subscales. Method: 309 women with infants aged up to 12 months completed the EPDS, BDI-II, BAI and the SCID-I. Results: Exploratory factor analysis revealed distinct anxiety and depression factors. Confirmatory factor analyses showed the identified two-factor model to be an adequate fit to the data and superior to a uni-dimensional model. Ail anxiety subscale score of 4 or more detected the presence of ail anxiety disorder with sensitivity of 63%, specificity 70%, positive predictive value of 45% and negative predictive value of 81%. Limitations: All participants were mothers with unsettled infants. a group that is known to have higher than average rates of depression and anxiety. The factor structure of the EPDS may have unique features in this group and so these results may not be generalizable to general postnatal samples. Also, participants in this Study ranged from I week to 12 months postpartum and there may be variations in the factor structure of the EPDS over this time. Conclusion: The 7-item depression subscale could be used in place of the total scale to identify women with major depression and the 3-item anxiety subscale could be used to identify women with anxiety disorders (occurring co-morbidly with depression or occurring alone). Future research should seek to replicate these findings in a general postnatal sample and to develop anxiety-specific screening tools for use in the postnatal period. (C) 2009 Elsevier B.V. All rights reserved.