Does the Edinburgh Postnatal Depression Scale measure anxiety?

Objective: The existence of a separate anxiety and depression dimension within the Edinburgh Postnatal Depression Scale (EPDS) has been reported previously. However, the concurrent validity of this anxiety subscale was never evaluated. We investigated whether (1) this existence of an anxiety subscale could be confirmed and (2) it more highly correlated with other measures of anxiety than the total EPDS. Methods: The SCL-90-R, the EPDS, and the State-Trait Anxiety Inventory (STAI) were filled out by 197 pregnant women. A principal component analysis (PCA) was used for confirmation of the subscales and correlations were computed between the (subscales of the) EPDS and the other measures of anxiety. Results: The existence of an anxiety scale within the EPDS was confirmed. However, this subscale did not yield higher correlations with other measures of anxiety than did the total EPDS. Conclusion: Investigators using the EPDS to screen for depression should realise that the instrument does not exclusively measure depression. It seems that both anxiety symptoms and depressive symptoms are more accurately measured when using the total 10-item EPDS than when using the subscales.