PHQ-9 Depression Scale
Patient Health Questionnaire-9 for major depressive disorder screening and severity assessment.
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Minimal or no depression (0–4). Typically does not require formal treatment.
- Evidence grade
- A
What it is and when to use it
The PHQ-9 (Patient Health Questionnaire-9) is a validated 9-item tool for screening, diagnosing, monitoring, and measuring the severity of major depression.
How to interpret it
Scores 0–4: Minimal/No depression; 5–9: Mild depression; 10–14: Moderate depression; 15–19: Moderately severe depression; 20–27: Severe depression.
Limitations and when not to use it
A high PHQ-9 score is not a standalone diagnosis; medical causes of mood disturbance (e.g. hypothyroidism) should be ruled out. Any score > 0 on Item 9 warrants emergency suicide risk assessment.
Frequently asked questions
- How often can the PHQ-9 be administered?
- The PHQ-9 can be repeated every 2–4 weeks to monitor treatment response and symptom remission over time.
Formulas and cut-offs are from the original authors of each score; see the references.
Last reviewed: June 2026
References
- Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606-613. PMID:11556941