Psychiatry
PHQ-9 (Depression)
Severity of depressive symptoms.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
The PHQ-9 is a brief, validated self-report questionnaire that screens for and measures the severity of depression. It comprises nine items corresponding directly to the diagnostic criteria for major depressive disorder, each rated from 0 (not at all) to 3 (nearly every day) over the previous two weeks, giving a total from 0 to 27. It is widely used in primary and secondary care to support diagnosis, grade severity and monitor response to treatment over time. The ninth item specifically asks about thoughts of self-harm.
Interpreting the result
Scores are banded as minimal (0–4), mild (5–9), moderate (10–14), moderately severe (15–19) and severe (20–27). A score of 10 or above has reasonable sensitivity and specificity for major depression and commonly prompts consideration of active treatment. Crucially, any positive response to item 9 requires immediate risk assessment regardless of the total. The score complements, rather than replaces, a clinical diagnostic assessment.
Worked example
A patient reports low mood, poor sleep, fatigue, poor concentration and reduced appetite most days, with no thoughts of self-harm, summing to a PHQ-9 of 16. This falls in the moderately severe band, supporting a discussion about active treatment alongside a full clinical assessment.
Critical actions
Any positive response to item 9 (self-harm) requires immediate risk assessment, regardless of total score.
Pearls / pitfalls
- It is a screening and severity tool, not a stand-alone diagnosis — confirm depression with a clinical assessment.
- A positive response to item 9 mandates immediate risk assessment whatever the total score.
- Physical symptoms (sleep, appetite, energy, concentration) can be driven by physical illness, so interpret somatic items in context.
- It is most powerful for tracking change over time; repeat scoring helps gauge treatment response.
Evidence & validation
Developed and validated by Kroenke, Spitzer and colleagues from the PRIME-MD instrument, with good reliability and criterion validity. It is recommended for the assessment and monitoring of depression in guidance including NICE and is widely used as a routine outcome measure.
Frequently asked questions
What PHQ-9 score indicates depression?
A score of 10 or above has reasonable accuracy for major depression and often prompts consideration of treatment. Bands run from minimal (0–4) through mild, moderate and moderately severe to severe (20–27).
Why is item 9 so important?
Item 9 asks about thoughts of self-harm or being better off dead. Any positive response requires an immediate risk assessment, regardless of the overall score, as it may signal acute risk.
Can the PHQ-9 diagnose depression on its own?
No. It is a validated screening and severity measure that supports, but does not replace, a clinical diagnostic assessment. The diagnosis is made by a clinician considering the full picture.
How is it used to monitor treatment?
Because it gives a numerical severity score, repeating the PHQ-9 over time tracks whether symptoms are improving with treatment. A falling score supports response, while a static or rising score may prompt review.
Can physical illness affect the score?
Yes. Several items cover sleep, appetite, energy and concentration, which can be affected by physical illness independent of mood. These somatic items should be interpreted in the clinical context.
References
- Kroenke K, Spitzer RL, Williams JBW. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606–613.
- NICE NG222: Depression in adults: treatment and management. 2022.
About the creator
Kroenke K, Spitzer RL et al.
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