Depression is one of the most disabling and costly illnesses worldwide. Globally, the total number of people with depression is estimated to exceed 280 million. Depression is associated with poor health and economic outcomes such as substance use disorders, HIV, educational impairments, and poverty. It is also a major risk factor for suicide, the cause of death of around 800,000 people every year. Depression is underdiagnosed and undertreated around the world. This is particularly the case in low-income countries, where data on the prevalence of depression as well as the resources to address it are scarce.

Measuring depression in these settings is an essential starting point to understand the magnitude of the problem, develop treatment programmes, monitor progress, and inform policy. In this post, we discuss how depression is defined and which tools exist to measure it. We conclude with some best practices to follow when using these tools in research studies conducted in low-resource settings.