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PHQ-9 Depression Screening: Complete Clinical Guide
The PHQ-9 is a 9-item self-report questionnaire based directly on DSM-IV major depression criteria. Each item is scored 0–3; the total ranges 0–27. A score ≥10 has 88% sensitivity and 88% specificity for major depressive disorder.
TL;DR: The PHQ-9 is a 9-item self-report questionnaire based directly on DSM-IV major depression criteria. Each item is scored 0–3; the total ranges 0–27. A score ≥10 has 88% sensitivity and 88% specificity for major depressive disorder. It diagnoses AND measures severity — making it uniquely useful for both initial screening and monitoring treatment response. It takes under 3 minutes to complete.
What Is the PHQ-9?
The Patient Health Questionnaire-9 was developed by Robert Spitzer, Janet Williams, and Kurt Kroenke as part of the PRIME-MD project. Published in 2001, it's the most widely validated depression screening tool in clinical medicine.
What makes the PHQ-9 distinctive is its direct correspondence to DSM diagnostic criteria. Each of the 9 items maps onto one of the nine DSM-IV major depression symptoms.
How to Calculate the PHQ-9
Each item scored: 0 = Not at all, 1 = Several days, 2 = More than half the days, 3 = Nearly every day
Over the last 2 weeks, how often have you been bothered by:
| # | Item | Score |
|---|---|---|
| 1 | Little interest or pleasure in doing things | 0–3 |
| 2 | Feeling down, depressed, or hopeless | 0–3 |
| 3 | Trouble falling or staying asleep, or sleeping too much | 0–3 |
| 4 | Feeling tired or having little energy | 0–3 |
| 5 | Poor appetite or overeating | 0–3 |
| 6 | Feeling bad about yourself | 0–3 |
| 7 | Trouble concentrating | 0–3 |
| 8 | Moving or speaking slowly, or being fidgety/restless | 0–3 |
| 9 | Thoughts that you would be better off dead or of hurting yourself | 0–3 |
Total PHQ-9 Score = sum of all 9 items (range 0–27)
Score Interpretation
| Score | Severity | Recommended Action |
|---|---|---|
| 1–4 | Minimal | Watchful waiting |
| 5–9 | Mild | Patient education; consider counseling |
| 10–14 | Moderate | Treatment plan: psychotherapy and/or pharmacotherapy |
| 15–19 | Moderately severe | Active treatment; pharmacotherapy typically indicated |
| 20–27 | Severe | Immediate treatment; assess for safety; psychiatry referral |
Item 9 safety flag: Any response other than "0" on item 9 requires direct clinical assessment regardless of total score.
Clinical Applications
Initial Screening in Primary Care
The PHQ-9 applied universally in annual health visits catches cases that might otherwise be missed.
Monitoring Treatment Response
The PHQ-9's quantitative nature makes it ideal for tracking treatment response.
Response: ≥50% reduction in score from baseline Remission: PHQ-9 <5
Case Vignettes
Case 1: 42-year-old woman with type 2 diabetes. PHQ-9 = 14. Moderate depression. Start sertraline; arrange psychotherapy referral; repeat PHQ-9 in 4–6 weeks.
Case 2: 28-year-old man returns after 6 weeks on escitalopram 10 mg. Baseline PHQ-9 = 16, new PHQ-9 = 9. Improvement (56% reduction) but not remission. Titrate escitalopram to 20 mg.
Case 3: 55-year-old post-MI patient. PHQ-9 = 12, item 9 = 1. Safety assessment triggered. Psychiatry co-management initiated.
Limitations and Considerations
The PHQ-9 is a screening tool, not a standalone diagnostic instrument. Confirm with clinical interview.
Somatic symptoms can inflate scores in medically ill patients. Consider the PHQ-2 as a first-step screen.
The PHQ-9 doesn't distinguish unipolar from bipolar depression. Ask about manic/hypomanic episodes before starting antidepressants.
Not validated for age <18. Use the PHQ-A (adolescent version).
Evidence and Guidelines
Kroenke K, Spitzer RL, Williams JBW (2001) published the original validation in 6,000 patients. A PHQ-9 cutoff of ≥10 yielded sensitivity 88% and specificity 88% for major depressive disorder. J Gen Intern Med. 2001;16(9):606–613. PMID: 11556941. DOI: 10.1046/j.1525-1497.2001.016009606.x
Kroenke K, Spitzer RL, Williams JBW (2003) validated the PHQ-2 as a two-item screener. Med Care. 2003;41(11):1284–1292. PMID: 14583691. DOI: 10.1097/01.MLR.0000093487.78664.3C
USPSTF recommends screening for depression in all adults ≥18 years (B recommendation).
Frequently Asked Questions
Q: Can I use the PHQ-9 for follow-up? Yes — track scores over time. Define response (≥50% reduction), remission (score <5), and relapse (score returning ≥10).
Q: What should I do if item 9 is positive? Stop and assess. Ask directly about suicidal ideation — frequency, plan, intent, means, and protective factors.
Q: How often should I repeat the PHQ-9 during treatment? At minimum: baseline, 4–6 weeks, and 8–12 weeks after starting treatment.
Related Calculators
- GAD-7 — generalized anxiety disorder severity
- PHQ-2 — ultra-brief depression pre-screen
- Columbia Suicide Severity Rating Scale — structured suicidality assessment
- MoCA — cognitive assessment
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. PMID: 11556941. DOI: 10.1046/j.1525-1497.2001.016009606.x
- Kroenke K, Spitzer RL, Williams JBW. The Patient Health Questionnaire-2. Med Care. 2003;41(11):1284–1292. PMID: 14583691.
- Löwe B, Decker O, Müller S, et al. Validation of the GAD-7 in the general population. Med Care. 2008;46(3):266–274. PMID: 18388841.
- U.S. Preventive Services Task Force. Screening for Depression in Adults. JAMA. 2023;329(23):2057–2067. PMID: 37338872.