The assessment of depression in the postnatal period: a comparison of four self-report questionnaires.

Objective: The objective of this study was to ascertain the degree of agreement between four self-report depression scales, with particular emphasis on whether each scale would identify the same subgroup of women as being 'most depressed'.

Method: The questionnaires were administered to a sample of approximately 200 postnatal women at 4 weeks, 4 months and 8 months after delivery. The instruments were: the Edinburgh Postnatal Depression Scale; the depression subscale of the Hospital Anxiety Depression Scale; the Zung Self-Rating Depression Scale; and the depression subscale of the Profile of Mood States.

Results: Agreement between pairs of instruments, in terms of identifying the most depressed subgroup of women in the cohort, only averaged approximately 40%. Agreement between the three instruments was only about 25%.

Conclusions: This poor level of agreement most likely reflects the different emphasis in item content of the questionnaires, which in turn reflects different notions of 'depression' held by the designers of the instruments. The implications of the findings for research and clinical practice are discussed.