PHQ-9 (Patient Health Questionnaire-9) Calculator

questionnaire

Little interest or pleasure in doing things

Feeling down, depressed, or hopeless

Trouble falling or staying asleep, or sleeping too much

Feeling tired or having little energy

Poor appetite or overeating

Feeling bad about yourself — or that you are a failure or have let yourself or your family down

Trouble concentrating on things, such as reading the newspaper or watching television

Moving or speaking so slowly that other people could have noticed — or the opposite, being so fidgety or restless that you have been moving around a lot more than usual

Thoughts that you would be better off dead, or of hurting yourself in some way⚠ Any positive response to this item requires immediate clinical assessment for suicidal risk.

✓ when to use

Use for depression screening in adults in primary care, outpatient, and inpatient settings. Suitable for initial detection, severity grading, and serial monitoring of treatment response (repeat every 2–4 weeks during active treatment). Endorsed by NICE, USPSTF, and multiple international guidelines for routine depression screening. Also used in research as a standardised outcome measure.

✗ when not to use

The PHQ-9 is a screening and severity measure, not a diagnostic tool in isolation — a positive screen requires clinical interview to confirm diagnosis. Not validated for children under 12 (use PHQ-A for adolescents). Scores may be elevated by somatic symptoms from medical illness (e.g., fatigue from anaemia, sleep disturbance from pain) — clinical judgement is required to differentiate. The PHQ-9 does not assess bipolar disorder — consider the MDQ if bipolarity is suspected before initiating antidepressants.

clinical pearls

Item 9 (suicidal ideation) is the single most important item clinically. ANY positive response (score ≥1 on item 9) requires direct clinical follow-up with a safety assessment — do not rely on the total score alone.
A score of ≥10 is the standard screening threshold for probable major depression (88% sensitivity, 88% specificity), but this is a screening cut-off, not a diagnosis. Always conduct a clinical interview to confirm.
The PHQ-9 is sensitive to change and is excellent for monitoring treatment response. A ≥5-point decrease is considered a clinically meaningful improvement. Failure to achieve at least a 50% reduction in PHQ-9 score by 6–8 weeks should prompt treatment review.
The first two items (Q1: anhedonia, Q2: depressed mood) form the PHQ-2, which can be used as an ultra-brief initial screen. A PHQ-2 score ≥3 should prompt completion of the full PHQ-9.
The PHQ-9 items reflect DSM criteria, so the questionnaire can also be used diagnostically: if 5+ items are scored ≥2 ('more than half the days'), and one of the first two items (depressed mood or anhedonia) is among them, this corresponds to the symptom count threshold for major depressive disorder. However, clinical interview remains the gold standard for diagnosis.

✓ when to use

✗ when not to use

clinical pearls

Item 9 (suicidal ideation) is the single most important item clinically. ANY positive response (score ≥1 on item 9) requires direct clinical follow-up with a safety assessment — do not rely on the total score alone.
A score of ≥10 is the standard screening threshold for probable major depression (88% sensitivity, 88% specificity), but this is a screening cut-off, not a diagnosis. Always conduct a clinical interview to confirm.
The PHQ-9 is sensitive to change and is excellent for monitoring treatment response. A ≥5-point decrease is considered a clinically meaningful improvement. Failure to achieve at least a 50% reduction in PHQ-9 score by 6–8 weeks should prompt treatment review.
The first two items (Q1: anhedonia, Q2: depressed mood) form the PHQ-2, which can be used as an ultra-brief initial screen. A PHQ-2 score ≥3 should prompt completion of the full PHQ-9.
The PHQ-9 items reflect DSM criteria, so the questionnaire can also be used diagnostically: if 5+ items are scored ≥2 ('more than half the days'), and one of the first two items (depressed mood or anhedonia) is among them, this corresponds to the symptom count threshold for major depressive disorder. However, clinical interview remains the gold standard for diagnosis.

PHQ-9 (Patient Health Questionnaire-9)

questionnaire

✓ when to use

✗ when not to use

clinical pearls

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