Patient Health Questionnaire-9 (PHQ-9)
Patient Health Questionnaire-9: Depression Scale · Also known as: PHQ-9, Patient Health Questionnaire Depression Module
The PHQ-9 is a brief, nine-item self-report questionnaire developed by Kroenke, Spitzer, and Williams to screen for and measure the severity of depressive symptoms. Published in 2001 in the Journal of General Internal Medicine, it has become one of the most widely used depression screening instruments globally. The scale maps directly to DSM-IV diagnostic criteria for major depressive disorder, making it valuable in both clinical and research settings.
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When to use it
Recommended for screening, symptom monitoring, and treatment response assessment in primary care, outpatient mental health, employee assistance programs, and research studies. Ideal when brief administration time is essential or repeated measures are needed over weeks or months. Validate any positive screen with clinical interview. Not a diagnostic instrument by itself; scores ≥15 warrant further evaluation. Suitable for adults and adolescents (age 12+); norms differ slightly in pediatric populations.
Strengths & limitations
- Excellent brevity and ease of administration—completed in 2–5 minutes by most respondents, reducing burden in busy clinical settings
- Strong psychometric properties—Cronbach's alpha 0.86–0.89, test-retest reliability r ≥ 0.80, with sensitivity and specificity both around 88% for major depressive disorder diagnosis
- DSM-IV criterion mapping—each item corresponds directly to DSM-IV symptoms, supporting diagnostic validity and clinical reasoning
- Validated in 50+ languages and diverse populations including primary care, psychiatry, obstetrics, general medicine, and community settings; effect sizes and thresholds often replicate across cultures
- Free public domain—not copyrighted; available at no cost from the author, facilitating widespread adoption
- Sensitive to treatment change—capable of detecting clinically meaningful shifts in symptom severity within weeks, making it suitable for outcome monitoring
- Does not diagnose—it screens and quantifies severity; a clinical interview is necessary to confirm major depressive disorder diagnosis and rule out bipolar disorder or secondary causes
- Susceptible to social desirability bias and reporting bias in self-report format; patient motivation or insight affects accuracy
- Fixed two-week recall window may miss seasonal patterns or shorter symptom fluctuations
- Less sensitive in severe depression or high suicide risk than clinician-rated instruments like HAM-D; does not explore psychotic or catatonic features
- Suicidal ideation item is binary (0 vs 1–3), potentially underestimating intensity; requires follow-up if endorsed
Frequently asked
Is the PHQ-9 alone enough to diagnose depression?
No. The PHQ-9 is a screening and severity measure, not a diagnostic instrument. A clinician must conduct a diagnostic interview to confirm major depressive disorder, rule out bipolar disorder, assess suicidality, identify secondary causes (medical, substance-related), and evaluate psychotic or catatonic features. A PHQ-9 score ≥10 is a signal for further evaluation, not a diagnosis.
What do I do if a patient scores 0–4 on PHQ-9?
A score of 0–4 indicates minimal or absent depressive symptoms. No mental health intervention is typically indicated; routine health maintenance continues. Reassure the patient and schedule follow-up as per normal care. If recent depressive episodes occurred or suicide risk is suspected, still conduct a brief interview despite the low score.
How should I handle the suicidal ideation item (question 9)?
Always assess question 9 directly. Any response of 1, 2, or 3 (several days, more than half the days, or nearly every day) requires immediate suicidal risk assessment using a standardized tool (e.g., Columbia-Suicide Severity Rating Scale) and possible emergency evaluation. Document the assessment and safety plan. Do not rely on the total score; prioritize this item.
Can I use PHQ-9 in adolescents and children?
The original validation was in adults (≥18 years), but subsequent studies support use in adolescents age 12–17 with good psychometric properties. Cutoffs may differ slightly (e.g., ≥11 in some adolescent populations). For children under 12, alternative instruments designed for younger ages are more appropriate.
How often should I repeat the PHQ-9 during treatment?
Frequency depends on clinical context. In acute care or medication trials, monthly or every 4 weeks is standard. In stable outpatient management, every 3 months is reasonable. In research, protocols dictate schedules (commonly baseline, 6 weeks, 12 weeks, end-of-treatment). More frequent administration (weekly) can help capture rapid fluctuations but may increase respondent burden.
Does the PHQ-9 change if a patient is grieving a loss?
Yes. Normal grief can temporarily elevate PHQ-9 scores because sadness, sleep disruption, and concentration difficulty are common in bereavement. Context is critical: distinguish clinical depression from grief-related sadness. Persistent impairment beyond 2 months, anhedonia, guilt about being alive, or suicidal ideation suggest depression requiring treatment, not simple grief.
Sources
- Kroenke, K., Spitzer, R. L., & Williams, J. B. (2001). The PHQ-9: validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613. DOI: 10.1046/j.1525-1497.2001.016009606.x ↗
- Kroenke, K., Spitzer, R. L., Williams, J. B., & Löwe, B. (2010). The Patient Health Questionnaire Somatic, Anxiety, and Depressive Symptom Scales: a systematic review. General Hospital Psychiatry, 32(4), 345–359. DOI: 10.1016/j.genhosppsych.2010.03.006 ↗
- Manea, L., Gilbody, S., & McMillan, D. (2012). Optimal cut-off score for diagnosing depression with the Patient Health Questionnaire (PHQ-9): a meta-analysis. CMAJ, 184(15), E682–E689. DOI: 10.1503/cmaj.110829 ↗
How to cite this page
ScholarGate. (2026, June 3). Patient Health Questionnaire-9: Depression Scale. ScholarGate. https://scholargate.app/en/clinical-psychology/phq-9
Which method?
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