PHQ-9
Summary and structure
The PHQ-9 (Patient Health Questionnaire-9) is a widely used self-report screening tool designed to assess the presence and severity of depressive symptoms. Developed by Kroenke, Spitzer, and Williams (2001), it is based directly on the nine diagnostic criteria for major depressive disorder from the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders).
Each of the nine items asks how often the respondent has been bothered by specific symptoms over the past two weeks, with response options ranging from “not at all” (0) to “nearly every day” (3). The total score ranges from 0 to 27, with higher scores indicating more severe depressive symptomatology.
Cut-off scores are typically interpreted as follows:
0–4 = minimal or no depression
5–9 = mild depression
10–14 = moderate depression
15–19 = moderately severe depression
20–27 = severe depression
The PHQ-9 can be used both as a screening instrument to identify possible depression and as a severity measure to monitor symptom change over time. Its brevity, clinical validity, and public-domain status have made it one of the most extensively used and validated depression measures worldwide.
Key Data
Age group: Adults (≥18 years)
Languages: Available in multiple languages
Intended Use
The PHQ-9 is intended for the screening, monitoring, and measurement of depression severity in clinical, primary care, occupational health, and research settings. It can be administered independently by patients or within structured clinical assessments. A total score of 10 or higher generally indicates the presence of clinically relevant depressive symptoms and should prompt further diagnostic evaluation or referral.
Beyond screening, the PHQ-9 is also used to track treatment progress and evaluate outcomes over time, making it particularly valuable in blended-care settings and digital therapeutic platforms. Because of its strong psychometric properties and international validation, it is well suited for routine use, large-scale studies, and integration into digital health tools to support early detection, ongoing monitoring, and stepped-care interventions.
Information for Practitioners
The PHQ-9 offers a validated, evidence-based framework for identifying and quantifying depressive symptoms. It aligns directly with DSM diagnostic criteria, allowing practitioners to efficiently detect major depressive disorder in medical or community settings.
A score of 10 or higher is the standard threshold suggesting likely depression; however, clinical judgment should always guide interpretation. Practitioners are advised to assess the impact on daily functioning (item 10: “If you checked off any problems, how difficult have these made it for you to do your work, take care of things at home, or get along with other people?”), which provides crucial contextual information about symptom burden.
When used in digital care environments, automated scoring and follow-up logic can facilitate triage, stepwise care, and documentation of clinical outcomes. The PHQ-9 is brief (takes about 2–4 minutes to complete) and is validated across medical, psychiatric, and general populations, making it an efficient tool for routine mental-health screening and progress monitoring.
Authors
Kurt Kroenke, M.D.
Robert L. Spitzer, M.D.
Janet B.W. Williams, Ph.D.
Scientific References
Kroenke K., Spitzer R.L., & Williams J.B.W. (2001). The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613. https://doi.org/10.1046/j.1525-1497.2001.016009606.x
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