The Patient Health Questionnaire-9 (PHQ-9) is the most widely used depression assessment tool in clinical practice. Developed by Kroenke, Spitzer, and Williams (2001) and published in the Journal of General Internal Medicine, it provides validated, standardized measurement of depression severity that corresponds directly to DSM diagnostic criteria.
The original validation study in over 6,000 primary care and OB-GYN patients established a PHQ-9 score of 10 or higher as identifying major depression with approximately 88% sensitivity and 88% specificity against structured clinical interview. This balance of sensitivity and specificity has made the PHQ-9 the default depression screener in American primary care and a key tool for measurement-based depression treatment.
What the PHQ-9 Measures
The PHQ-9 has 9 items asking how often, over the past 2 weeks, you’ve been bothered by:
- Little interest or pleasure in doing things
- Feeling down, depressed, or hopeless
- Trouble falling/staying asleep or sleeping too much
- Feeling tired or having little energy
- Poor appetite or overeating
- Feeling bad about yourself, being a failure, letting yourself or family down
- Trouble concentrating on things
- Moving or speaking so slowly others noticed, or being fidgety/restless
- Thoughts of being better off dead or hurting yourself in some way
Each item is scored 0-3. Total score ranges from 0 to 27. A 10th question asks about functional impact. Each PHQ-9 item maps directly to one DSM criterion for major depressive disorder.
Score Interpretation
Per the original Kroenke et al. (2001) validation and standard clinical use:
- 0-4: Minimal depression
- 5-9: Mild depression — monitoring; sometimes intervention
- 10-14: Moderate depression — treatment generally warranted
- 15-19: Moderately severe depression — treatment essential
- 20-27: Severe depression — typically urgent treatment
The 10+ threshold remains the standard clinical action point.
Special Attention to Item 9
Item 9 asks about thoughts of self-harm or being better off dead. Any positive response — even “several days” — warrants attention. Most clinicians follow up directly on this item regardless of total score. Suicidal ideation in depression should always be evaluated specifically, not just averaged into total score.
Psychometric Properties
The PHQ-9 has been extensively validated across populations, languages, and clinical settings:
- Original validation: 88% sensitivity, 88% specificity at threshold of 10
- Subsequent meta-analyses consistently support 10+ as balanced threshold
- Individual patient-data meta-analyses (Levis et al., 2019) pool sensitivity and specificity both around 0.85 at this threshold
- Validated for tracking treatment response, not just initial screening
- Strong test-retest reliability
- In the public domain; free to use without permission
What PHQ-9 Is Good For
Screening
Identifying patients with significant depression in primary care, OB-GYN, psychiatry, and other settings.
Severity assessment
Standardized measure of depression severity supporting treatment decisions.
Treatment tracking
Repeated PHQ-9 shows treatment response over time. Reduction of 5+ points typically represents meaningful clinical improvement. Less than 50% reduction at 8 weeks suggests need for treatment adjustment.
Remission target
Treatment goal is typically PHQ-9 below 5 — full remission, not just response. STAR*D and subsequent trials demonstrate better long-term outcomes when remission (not just response) is achieved.
Measurement-based care
Systematic PHQ-9 use as part of measurement-based care has been associated with substantially better outcomes than treatment without standardized tracking — published meta-analyses show 17-40% improvement over treatment-as-usual.
What PHQ-9 Is Not Good For
Definitive diagnosis
High score suggests depression; doesn’t make diagnosis. Clinical evaluation considers PHQ-9 alongside history, examination, and differential diagnosis.
Distinguishing depression types
Doesn’t distinguish unipolar from bipolar depression, atypical from melancholic features, or grief from depression. Clinical context essential.
Detecting all depression presentations
Anhedonia-predominant or somatic-predominant presentations may produce lower scores than functional impairment suggests.
Capturing mood reactivity
PHQ-9 reflects symptoms over 2 weeks; doesn’t capture mood reactivity patterns suggestive of atypical features or bipolar.
Using PHQ-9 in Treatment
Initial measurement
Baseline at start of treatment for comparison.
Response tracking
Every 4-8 weeks during active treatment. Some practices use weekly PHQ-9 for more granular tracking.
Adjustment trigger
If less than 50% reduction at 8 weeks, treatment intensification typically warranted per APA guidelines.
Remission goal
PHQ-9 below 5 indicates full remission — the treatment target supported by STAR*D and other research showing better long-term outcomes with remission vs. response only.
Maintenance tracking
Periodic PHQ-9 during maintenance can detect early recurrence and support timely intervention.
Source: Kroenke et al. (2001), Levis et al. (2019), STAR*D trial data.
Partial response acceptance
Depression treatment without standardized measurement often settles for partial response — leaving substantial residual symptoms and elevated relapse risk.
Measurement-based care
Dr. Farkas uses PHQ-9 systematically — tracking response objectively and adjusting treatment until full remission.
Real remission
Patients achieve documented full remission — not just “feeling better” but actually well — with reduced long-term relapse risk.
Common Questions About PHQ-9
My score went from 18 to 9. Is that good?
It’s meaningful improvement (50% reduction is the typical response threshold). But the evidence-based goal is typically PHQ-9 below 5 — full remission. Per STAR*D and subsequent research, continued treatment to achieve remission produces better long-term outcomes than stopping at response.
What if I score 5 but still feel bad?
Worth discussing with your clinician. PHQ-9 has limitations, and clinical impression matters too. Some patients have symptoms not well-captured by PHQ-9 items.
Will my answer to item 9 trigger something?
Any positive response warrants follow-up discussion — but rarely triggers automatic intervention like hospitalization. Honest answers help your clinician help you. See our related articles on major depression and recurrent depression.
Should I keep my own PHQ-9 record?
For interested patients, tracking your own scores can support self-awareness and treatment engagement. The PHQ-9 is in the public domain and freely available.