Screening for depression during and after pregnancy

Kirsten Holdt Henningsen

The Norwegian Knowledge Centre for the Health Services (NOKC) published in January, 2013 a report based on a literature review on screening for depression in pre- or postnatal women. Its aim was to inform the Norwegian “National Council for priority setting in health care” on the accuracy of the screening and on the effects that could be expected. Since pregnancy and the postpartum are a period during which women have frequent contacts with the healthcare system, it seemed useful to investigate whether it is appropriate to introduce screening for pre- and postnatal depression.

1. Background

Depressive symptoms are very common during pregnancy and in the period after giving birth. Untreated depression poses risks to the mother as well as to her child. A mother, who suffers from depression, has an increased likelihood of engaging in risky behaviors and facing psychosocial problems which, in turn, can have negative consequences for the development of her child.
Identification of whether the woman has a clinical depression, depressive symptoms or is downcast is key in view of the effective interventions that are possible, which consist of treatment and support for the mother, the child and the whole family. 

2. Main results

2.1 Screening tests accuracy for identification of depression:
The Edinburgh Postnatal Depression Scale (EPDS), a 10-item questionnaire developed to detect women with postpartum depression, was identified as the most commonly used instrument in studies looking at accuracy and effect. Items of the EPDS scale correspond to various clinical depression symptoms and overall assessment is done by total score, with higher scores indicating more depressive symptoms. A score ≥ 10 was used as a cut-off in this report.

• EPDS identified 93 percent (95% CI: 85 to 97) of the postpartum women with clinical depression (sensitivity).
• EPDS identified 78 percent (95% CI: 68 to 97) of the postpartum women without clinical depression as healthy (specificity).
• The specificity of 78% means that 22% of the women without clinical depression were classified at risk for developing depression (false positives) with the use EPDS.

The investigators at NOKC provide the following example:

If ten percent of women are depressed after birth, in a random 1000 there will be 100 depressed women and 900 healthy ones. If all the 1000 women are screened with EPDS (cut off ≥ 10) we can expect that 93 of the 100 women with depression will be identified. However, 198 of the 900 healthy ones will be wrongly identified as depressed (false positive). Thus, over the 1000 women screened, the EDPS will indicate a depression in 291 individuals whereas only 93 genuinely suffer from depression. In other words, a positive EDPS in this population will indicate a true depression in only 32% (93/291). Among the screened women who have a negative test the possibility of them actually having a depression is 1 percent (7/(702+7). 

2.2 Effect of screening in combination with intervention for depressive symptoms:

• There is high-level evidence that adding a postnatal programme including screening with EPDS and intervention brings down the prevalence of depressive symptoms in the period four to six months after birth from 10% to 6% (95% CI: 5% to 8%). This evidence is based on four randomised controlled trials and two observational studies, with a total of 5052 participants.
• The method used to assess depressive symptoms varied amongst the included studies (was for example based on a clinical examination or collected retrospectively from journal notes), but the prevalence of confirmed clinical depressions amongst the included participants is not clear. All interventions were psychosocial interventions (non-pharmacological) with variations within the support offered and within the follow-up period.
• No studies reported physical or social outcomes for the mother, and no negative or adverse effects of screening or intervention for the mother, child or family were reported either.

Conclusions

EPDS is the most common test used both in the accuracy and the efficacy studies. Postnatal screening with EPDS, combined with intervention reduces the proportion of women with depressive symptoms at 4-6 months by about 40% (Odds Ratio 0.60; 95% CI 0.49 to 0.75) compared to no screening. This means that, in Norway, 4 to 6 months after birth, the probability for women in the non-screened group having depressive symptoms is 10 percent versus 6 percent (from 5 to 8 percent) in the screened group. Most women with (risk of) depression will effectively be picked up (9 of the 10), but there will also be a significant number of women (approximately 20% of the whole group) classified as at risk for developing depression, while they are in fact not depressed (false positives).
The study further concludes that there is a need for further research. Screening with EPDS should be performed within a large controlled study with a long-term follow-up aimed at evaluating the clinical effect while gathering data on quality of life and resources used. Among the research gaps identified are the need for studies focusing on pregnant women, studies with a long-term follow-up and studies focusing also on other outcomes than depression, including outcomes for the child. 

Reference

1. Larun, L. Fønhus MS, Håvelsrud K, Brurberg KG, Reinar LM. Depresjonsscreening av gravide og barselkvinner (Rapport fra Kunnskapssenteret no. 1−2013. Oslo: Nasjonalt kunnskapssenter for helsetjenesten, 2013.
2. The report can be retrieved from the NOKC website https://www.fhi.no/ (see “Publications”, 2013).