In 2022, the Canadian Task Force on Preventive Health Care released recommendations against using a tool (the Edinburgh Postnatal Depression Scale – EPDS) to screen for depression during pregnancy and the postpartum. These recommendations do not agree with those made by experts in B.C. and Ontario; and around the world in Australia, the United States, England and Scotland.
It is important that we look closely at these recommendations and try to understand why they differ.
Depression during pregnancy and the postpartum is common, affecting 10-15 per cent of women and 8–12 per cent of men (unfortunately, there is no research to tell us how common depression during pregnancy/postpartum is among birth fathers or non-binary and gender diverse individuals). Rates are even higher amongst marginalized groups, affecting almost half of immigrant women and Indigenous women. Relatedly, suicide is a leading cause of maternal death in Canada.
It doesn’t have to be this way.
Depression can be treated successfully. I know this not only because that is what evidence from research demonstrates, and clinicians tell me, but because it is my personal experience. I have recovered from depression and am so grateful to the clinicians who have helped me with treatment along the way. Early intervention and treatment during pregnancy or postpartum can help not only the suffering parent, but the whole family, and prevent long-term negative outcomes for children and families.
It can be tricky to recognize depression during pregnancy and the postpartum. Many symptoms – changes in sleeping, eating, concentrating, physical changes – are natural parts of bringing a child into this world. This is why the EPDS is so useful – it is a tool specifically developed to disentangle the experience of pregnancy and postpartum from symptoms of depression. It is reliable and valid, and has become the gold standard for depression screening during pregnancy and postpartum. In Canada, it is already part of the prenatal/postpartum medical records in more than two thirds of our provinces/territories.
Why, then, does the Canadian Task Force on Preventive Health Care recommend against using it?
The systematic review on which their recommendation was based used extremely strict inclusion criteria to determine what evidence was included, and as a result, only one randomized controlled trial (RCT) was identified as eligible. This RCT found that participants who were screened with the EPDS had improved maternal mental health outcomes as measured by the EPDS at six months postpartum. However, the Canadian Task Force on Preventive Health Care reached the conclusion that the evidence in support of using the EPDS was “very uncertain, owing to very serious risk-of-bias concerns (use of self-reported outcome measures and selective outcome reporting) as well as imprecision concerns because there was only a single small trial.”
With regard to the task force’s critique of the self-reported nature, this tool has been accepted and endorsed by the clinical and academic community as the gold standard for depression screening in the context of pregnancy and postpartum. With regard to the charge of “selective outcome reporting”, there is evidence of outcome switching in favor of the EPDS, for which results were stronger, however, outcomes were reported for both the EPDS and the General Health Questionnaire (GHQ). While it seems reasonable to me that there could be some risk of bias, the rating of very serious risk of bias seems unjustified. Indeed, this same RCT was assigned the highest quality rating of “good” in a systematic review by the U.S. Preventive Services Task Force.
The claim that this RCT was the only relevant evidence in support of the EPDS ignored the five additional “fair-quality” trials that the U.S. task force deemed acceptable to include, as well as a rich non-RCT evidence base. Multiple experts who served as peer reviewers for the Canadian task force pointed out the inadequacy of considering only RCT evidence in support of tool-based perinatal depression screening, but their input was dismissed (as detailed in the Reviewer’s Comments document).
On the other hand, the Canadian task force did consider non-RCT evidence to support its claim that instrument-based perinatal depression screening could be harmful in terms of false positives and overdiagnosis, and related impacts on Canada’s health-care system. If the concern is truly the risk of false positives, the task force could recommend the adoption of a higher cut-off score on the EPDS. The RCT used a cut-off score on the EPDS of 10 or above, which is often chosen to minimize the risk of missing cases of depression (false negatives), and has a specificity of 84 per cent. A more common cut-off score used in clinical practice of 13 or higher has a specificity of 95 per cent, which results in a lower number of false positives.
This brings me to the task force’s concern about constrained resources in our health-care system. In this same guideline, it recommends that: “When caring for individuals in the pregnant and postpartum period, clinicians should continue to ask about mood or other symptoms of depression, maintain a high degree of vigilance for symptoms and signs of depression, and investigate accordingly.” Why not use the tool that has been developed specifically for this purpose to support this conversation? The EPDS is quick (10 questions) and easy to administer; it won’t take longer than the clinician having a conversation about mental health with a patient. But it will serve as a reminder and provide structure for a clinician to do the screening. A study in Alberta estimated that 2,000 cases of postpartum depression that are being missed in usual care could be detected with consistent implementation of screening using the EPDS.
The scale also may be one way to mitigate inequities in health screening for racialized patients. Research has shown that when perinatal depression screening is left to the discretion of the health-care provider, racialized patients are less likely to get screened. The task force acknowledged the potential for negative impact of its recommendation on marginalized groups but did not indicate a rationale for giving other concerns more weight than this one.
The task force is further concerned about lack of resources to manage those whose screen suggests the need for further evaluation. The health-care system is certainly strained, and lack of specialist perinatal mental health care is a real problem. However, the non-profit sector has been stepping up to meet these needs. Patients can be connected with a variety of organizations, such as the Pacific Postpartum Support Society, Canadian Mental Health Association, Life With A Baby and PSI Canada, all of whom provide support for people experiencing perinatal mental health challenges.
I do want to acknowledge and appreciate that the task force recommendation is conditional. An encouraging aspect of the rating of very low certainty for the evidence is the implication that further research has a greater chance of changing the task force recommendation.
On the other hand, there are things that I find discouraging. I note that in the GRADE system used by the task force, when “the margin between desirable and undesirable consequences is small, the balance depends on patient values and preferences.” Given that the task force reached the conclusion that the evidence in favour of the benefits of instrument-based screening was very uncertain, and that there was limited evidence of harms, shouldn’t the task force have given greater weight to its patient preferences study? This study concluded that: “The majority of participants indicated a strong desire to be screened for depression during pregnancy or the postpartum period, even considering that the likelihood of many of the outcomes are not well known.” Further, patients in the study felt that “treatment decisions [are] separate from screening decisions, and any impacts from false positives or overdiagnosis would be resolved quickly.”
Most disheartening to me is that the task force guideline states: “Although no evidence was found on the harms of screening in our systematic review, evidence from other sources described below suggests the time and focus on screening could reduce opportunities to discuss other aspects of health during a perinatal primary care encounter.” This is what it boils down to: The Canadian Task Force seems to believe that other things are more important than screening for mental illness.
I argue that it is of the utmost importance that we try to prevent perinatal suicides and promote mental health for Canadian families. Let’s use the tools we have to do that.