Up to 50% of all cases of postpartum depression go undetected. The Edinburgh Postnatal Depression Scale (EPDS) has been the only instrument available that was specifically designed to screen for this mood disorder. None of the items on the EPDS, however, are written in the context of new motherhood.
The purpose of this study was to further assess the construct validity of the newly designed Postpartum Depression Screening Scale (PDSS) along with its sensitivity, specificity, and predictive values.
A total sample of 150 mothers within 12 weeks postpartum participated in the study.
Each mother completed in random order three questionnaires: The PDSS, EPDS, and The Beck Depression Inventory-II (BDI-II). Immediately after completing these three questionnaires, each woman was interviewed by a nurse psychotherapist using the Structural Clinical Interview for DSM-IV Axis 1 Disorders.
Twelve percent (n = 18) of the mothers were diagnosed with major postpartum depression, 19% (n = 28) with minor postpartum depression, and 69% (n = 104) with no depression. The PDSS was strongly correlated with both the BDI-II (r = 0.81) and the EPDS (r = 0.79). The ability of the PDSS to explain variance in diagnostic classification of postpartum depression above that explained by the BDI-II and EPDS (i.e., incremental validity) was assessed using hierarchical regression. After explaining variance in group classification by the other two depression instruments, the PDSS explained an additional 9% of the variance in depression diagnosis. Using receiver operating characteristic (ROC) curves, a PDSS cut-off score of 80 (sensitivity 94% and specificity 98%) is recommended for major postpartum depression and a cut-off score of 60 (sensitivity 91% and specificity 72%) for major or minor depression.
Based on the results of this psychometric testing, the PDSS is considered ready for use in routine screening of mothers.