Screening for postnatal depression using the double-test strategy

Postnatal depression affects 10% to 15% of women after childbirth. Self-report rating instruments, such as the Edinburgh Postnatal Depression Scale (EPDS), have been developed and administered to postpartum women to facilitate early detection. Most postnatal depression screening scales, however, focus solely on depressive symptomatology. We hypothesized that applying two complementary rating scales of symptoms and functioning as a double test would significantly enhance the positive predictive value of screening.

A prospective cohort study was conducted at the postnatal clinic of a university teaching hospital. One hundred forty-five Chinese women completed the EPDS and 12-item General Health Questionnaire (GHQ) 6 weeks after delivery. They were then interviewed by a psychiatrist, who used the Structured Clinical Interview for third revised edition of the Diagnostic and Statistical Manual of Mental Disorders, nonpatient version (SCID-NP), to validate the diagnoses.

The positive predictive value of the EPDS and GHQ, when administered independently, was 44% and 52%, respectively, at their respective optimal cutoff scores. When the EPDS-GHQ double test was administered, the positive predictive value was significantly increased to 78%.

Simultaneous administration of the EPDS and GHQ can substantially improve identification of women with postnatal depression. This can potentially reduce unnecessary referrals to general practitioners and psychiatrists and may enhance the overall cost-effectiveness of population-wide screening.