Validity of two case finding questions to detect postnatal depression: a review of diagnostic test accuracy

Background: Postnatal depression (PND) is a serious condition associated with negative consequences for the wellbeing of mother and infant. In the UK routine screening for PND is not currently recommended, although the use of two case finding questions in routine practice to identify PND has been advocated in policy guidance. The diagnostic test accuracy (DTA) of the two questions has been reviewed in general population samples; however a review of their validity in postnatal populations is unknown. The aim of this rapid review was to identify studies of DTA of two case finding questions (2CFQ) for PND detection.

Methods: DTA studies were included which compared the 2CFQ to gold standard diagnostic criteria. Sources searched included Medline, PsychInfo, Medion, ARIF and cited reference search via Web of Science.

Results: Seven studies were identified which used a two question instrument to detect PND. Only one study compared the 2CFQ to standardised diagnostic criteria in a USA postnatal population. The test reported 100% sensitivity and 62% specificity at 4 postnatal weeks. The test was excellent at 'ruling out' PND given a negative response to both questions. False positive rates were high indicating unnecessary follow-up for a substantial number of women.

Conclusion: The review found limited evidence for use of the 2CFQ approach to detect PND. Further primary research should be undertaken to assess the DTA of the 2CFQ approach recommended for use in UK postnatal populations; this will ultimately inform the utility of current UK policy guidance.