What is the purpose of the Patient Health Questionnaire (PHQ-9)?

The Patient Health Questionnaire (PHQ-9) is specifically designed to assess the severity of depression. It comprises nine questions that correspond to the criteria for major depressive disorder, allowing healthcare providers to evaluate how the patient has been feeling over the past two weeks. The instrument quantifies the symptoms of depression and provides a score that ranges from 0 to 27, which can help determine the severity of depressive symptoms—ranging from mild to severe. This scoring system aids in tracking changes in symptoms over time and informs treatment decisions.

While other tools and questionnaires assess different areas of mental health, the PHQ-9 is focused solely on depression, making it an essential instrument in both clinical practice and research for monitoring the impact of depression on individuals.