Clinicians treat the majority of mental illnesses in the primary care setting. However, due to a lack of specialists and expertise in the diagnosis and treatment of mental illnesses within primary care, health systems are increasingly funding models of behavioral health integration. Depression is one of the most common mental illnesses seen in primary care, and current guidelines recommend screening all patients for depression when integrated models of care exist. However, this may cause harm and may not be the best use of resources. 

If you regularly visit your primary care doctor, chances are you have answered screening questions about your mood during one of your visits. Current recommendations in the United States are to screen the general population for depression in primary care settings in the context of integrated systems for managing mental illnesses. However, guidelines in other countries—such as the NICE guidelines in the United Kingdom and the Canadian Task Force on Preventative Health Care—recommend against screening the general population for depression. Below are common questions about depression screening.

What Does Current Screening for Depression Look Like and Why is It Recommended in the United States?

Screening questionnaires for depression are used to identify patients with depression who have not yet been identified. However, in practice depression screening questionnaires are often used to track depression symptom severity, to monitor treatment effects, and to detect relapse in people with a known history of depression–none of these technically constitute screening.

Screening for depression is only useful if it leads to improved outcomes. For a screening tool to be effective, it should identify patients in whom the condition has not already been diagnosed, and it should result in patient engagement in treatment. It should obtain improved health outcomes to warrant the costs and potential harms.

In the United States, nationwide screening is supported by the drug industry and the Patient Health Questionnaire-9 (PHQ-9), one of the most commonly used screening tools for depression in primary care that was developed by a pharmaceutical company (Pfizer).

National Institute for Health and Clinical Excellence (NICE) and Canadian Task Force on Preventive Health Care (CTFPHC) Guidelines

Guidelines from Canada and the UK have raised important concerns about the routine screening for depression in primary care. Both NICE and CTFPHC guidelines do not recommend depression screening due to a lack of empirical evidence showing that screening improves outcomes, as well as the high rate of false positives (greater than 50%). The high cost of screening also diverts resources from people with more serious mental illnesses.

US Preventive Services Task Force (USPSTF) Recommendations

The USPSTF recommends screening patients for depression if systems are in place to ensure an accurate diagnosis, treatment, and follow-up. However, in the development of these recommendations, none of the trials cited as evidence supporting depression screening actually evaluated screening, as patients were required to have depressive symptoms or a diagnosis of depression in order to be eligible. Rather, the trials evaluated interventions for depression that were made available to either intervention or control patients.

Does Screening for Depression Help Patients?

Approximately 50% of positive screening results in primary care are false positives, and this number would certainly be much higher with repeated screenings.  Unfortunately, studies on the effect of treatment with antidepressants show that clinical improvement in patients with depression are minimal, especially when all studies are included (not just published studies). Effects are even smaller among people with mild symptoms. The NICE guidelines recommend against treatment with medications for mild symptoms of depression in primary care due to a poor risk-benefit ratio. According to a meta-analysis, psychological treatments are effective in treating depression in primary care if patients are referred by their physician and not recruited through screening.

Harms of Screening

According to the British physician Sir Muir Gray, “All screening programmes do harm; some do good as well.” As with any intervention, clinicians should consider the harms of screening for depression in primary care. A positive screen may result in the misdiagnosis of depression, medication treatment of mild symptoms that would have resolved on their own, and adverse effects as a result of medication treatment. Allocating resources to screening may also divert resources from people with known severe mental illness in health systems that are already struggling financially.

Recommendations

Primary care clinicians routinely screen their patients for depression based on the USPSTF guidelines. However, screening patients is resource-intensive and should be reconsidered. The benefits of screening for depression still have not been proven, whereas the harms of screening are known. Health systems should instead prioritize using available funds to improve the treatment of people with known mental illnesses.