The psychometric properties of the Icelandic version of the Edinburgh Postnatal Depression Scale (EPDS) when used prenatal

Abstract

ObjectiveTo evaluate the psychometric properties of the Icelandic version of the Edinburgh Postnatal Depression Scale (EPDS) when used prenatal, explore the dimensionality of the scale and describe its effectiveness in identifying depression. DesignA sample of Icelandic women filled in the EPDS at week 16 gestation, week 24 and week 36. If screened positive in week 16 they were asked to attend a psychiatric diagnostic interview 2–4 weeks later. Every 10th woman screened negative was also asked to attend an interview. SettingAntenatal clinics at primary health care centres in Iceland. ParticipantsIn total, 2512 women receiving prenatal care participated in the study. At week 16 gestation, 2397 women filled in the Edinburgh Postnatal Depression Scale, 2025 at week 25, and 1756 at week 36. 474 women attended diagnostic interview two to four weeks after screening. Measurements and findingsInternal reliability, convergent validity and test-retest correlation of the Icelandic version of the Edinburgh Postnatal Depression Scale appeared acceptable. An exploratory factor analysis supported a one-factor structure of the Edinburgh Postnatal Depression Scale that was confirmed by confirmatory factor analysis showing best fit for one general factor with two group factors. A cut-off score of 11 or higher had specificity of 0.89, sensitivity of 0.80 and positive predictive value of 0.44. Key conclusions and implications for practiceThe Icelandic version of the Edinburgh Postnatal Depression Scale is a valid and reliable one-dimensional instrument suitable to screen for depression prenatally. We recommend using score 11 or higher as a cut-off. If women score 11, they should be re-assessed two weeks later, but if they score 12 or higher, they should be referred directly for a further assessment. A time gap of two to four weeks does weaken the scale's ability to discriminate between those suffering from Major Depression and those who screen negative.