PHQ-9: Patient Health Questionnaire-9

The PHQ-9 (Patient Health Questionnaire-9) is a 9-item self-report questionnaire that screens for depression and rates its severity over the past two weeks. Each item scores one DSM criterion from 0 to 3, for a total of 0 to 27 ^[1].

Why the PHQ-9 matters in practice

Picture a 34-year-old client who comes to primary care with persistent fatigue and difficulty sleeping. Rather than relying on subjective assessment alone, the PHQ-9 returns a score of 16 (moderately severe depression), quantifying symptoms that might otherwise go undetected or undertreated.

Foundational context

The PHQ-9 is the depression module of the Patient Health Questionnaire, a self-administered version of the PRIME-MD diagnostic tool ^[1]. Its direct correspondence to DSM diagnostic criteria lets clinicians identify symptoms consistent with major depressive disorder while also capturing functional impact.

It is widely used in primary care, specialty mental health, and research for initial screening, monitoring treatment response, and supporting measurement-based care.

What does the PHQ-9 measure?

The PHQ-9 is a multipurpose scale for screening, monitoring, and measuring the severity of depression to support clinical evaluation. It was developed by Kurt Kroenke, Robert Spitzer, and Janet Williams, and scores each of the 9 DSM-IV criteria for depression ^[1].

Each item is scored from 0 (not at all) to 3 (nearly every day), yielding a total score range of 0-27. The original validation found it a reliable and valid measure of depression severity ^[1].

The PHQ-9 captures symptoms of depression experienced over the past two weeks, including:

• Anhedonia (little interest or pleasure)
• Depressed mood
• Sleep disturbances
• Fatigue or low energy
• Appetite changes
• Feelings of worthlessness or guilt
• Concentration difficulties
• Psychomotor changes (moving slowly or being fidgety)
• Thoughts of death or self-harm (Item 9)

Screening vs. diagnosis

The PHQ-9 is a screening and monitoring tool that identifies people who may benefit from further evaluation. While a score ≥10 has good sensitivity and specificity for major depression, a full clinical evaluation by a qualified professional is required to confirm a diagnosis.

PHQ-9 in clinical practice

Used in primary care, specialty mental health, hospitals, and community settings for initial assessment, treatment monitoring, and outcome measurement.

How do you give the PHQ-9?

Self-report format

Clients complete the questionnaire independently, rating how often they've experienced each symptom over the past 2 weeks. It can be completed on paper or digitally.

Quick administration

Takes 2-5 minutes to complete. Scoring is straightforward: simply sum the values for all nine items.

Regular monitoring

Typically administered at intake, then periodically throughout treatment (e.g., every 2-4 weeks) to track symptom changes and treatment response.

Suicide risk assessment

Item 9 specifically asks about suicidal thoughts. Any positive response requires immediate clinical follow-up and safety assessment.

Best practices

• Ensure clients understand they're rating symptoms over the past 2 weeks
• Review responses with the client, particularly item 9 (suicidal ideation)
• Consider cultural and linguistic factors; use a validated translation where one exists
• Integrate scores with clinical judgment, don't rely solely on numbers

How do you score and interpret the PHQ-9?

The PHQ-9 produces a total score between 0–27. Scores of 5, 10, 15 and 20 mark mild, moderate, moderately severe and severe depression ^[1].

Severity thresholds:

• 0–4: Minimal/None. No action typically required.
• 5–9: Mild. Watchful waiting; repeat at follow-up.
• 10–14: Moderate. Treatment plan: counselling, follow-up, or pharmacotherapy.
• 15–19: Moderately Severe. Active treatment with pharmacotherapy and/or psychotherapy.
• 20–27: Severe. Immediate treatment; consider referral to specialty care.

Clinical threshold:

• ≥10 had 88% sensitivity and 88% specificity for major depression against a structured mental health professional interview ^[1].

Item 9 (suicidal ideation):

• Any score ≥1 requires immediate clinical follow-up and safety assessment, regardless of total score.

What is a good PHQ-9 score?

A "good" PHQ-9 score is 0-4, the minimal range ^[1]. Scores in this range suggest that depressive symptoms are not significantly affecting daily functioning, and no clinical intervention is typically needed.

In treatment monitoring, reaching the minimal range (below 5) is a common target.

However, context matters. For someone currently in treatment for depression, a score of 5-9 (mild depression) might represent significant improvement from an initial score of 20 (severe depression). In this case, the trajectory is more important than the absolute number.

A single "good" score doesn't tell the whole story. Trends over time, functional impairment, and individual client context are equally important in clinical decision-making.

Monitoring treatment response

A change of 5 points or more was the minimal clinically important difference for individual change in a late-life depression trial ^[3]. Track changes over time to assess treatment effectiveness.

If scores aren't improving after 4-6 weeks of treatment, consider adjusting the treatment plan, increasing intervention intensity, or seeking consultation.

Diagnostic considerations

A score of 10 or greater had 88% sensitivity and 88% specificity for major depression in the original validation ^[1]. However, the PHQ-9 is a screening tool, not a substitute for clinical diagnosis.

Always conduct a full clinical evaluation before making treatment decisions based on PHQ-9 scores.

Critical: item 9 assessment

Any score ≥1 on item 9 (suicidal thoughts) requires immediate safety evaluation and appropriate intervention, regardless of total PHQ-9 score.

What treatment fits each PHQ-9 score?

PHQ-9 scores guide intervention intensity, but clinical judgment remains essential. These are starting points, not rigid protocols.

Minimal/none

Action: No treatment indicated. Reassess if symptoms emerge, and provide psychoeducation on depression warning signs.

Mild depression

Action: Watchful waiting with repeat assessment at follow-up. Consider behavioural interventions (exercise, sleep hygiene, stress management).

If symptoms persist or worsen, initiate treatment. Client preference for counselling or medication should guide intervention.

Moderate depression

Action: A treatment plan, such as counselling, follow-up, or pharmacotherapy. Psychotherapy options include CBT and IPT.

Reassess regularly. If there is no improvement, consider treatment intensification or psychiatric consultation.

Moderately severe depression

Action: Active treatment with pharmacotherapy and/or psychotherapy. Consider psychiatric referral if there is no prior specialty care.

Follow up closely and reassess suicide risk at each visit.

Severe depression

Action: Immediate treatment and consideration of referral to specialty mental health care. Assess for higher levels of care if there are safety concerns, psychotic features, or poor response to treatment.

Monitor closely until stabilized.

Remember: PHQ-9 scores are one data point. Integrate with client history, functional impairment, comorbidities, and clinical presentation. A client with a moderate score but severe functional impairment may need more intensive treatment than scores alone suggest; pairing the PHQ-9 with the WSAS quantifies that functional impairment directly.

Psychometric properties

• Original validation. The PHQ-9 was completed by 6,000 adults in 8 primary care and 7 obstetrics-gynecology clinics, with criterion validity tested against an independent structured mental health professional interview in 580 of them. As scores increased, functional status decreased on all six SF-20 subscales, and results were similar in both settings ^[1].
• Treatment monitoring. In a late-life depression trial, test-retest reliability over 7 days was excellent, responsiveness to treatment was at least equal to the SCL-20, and the minimal clinically important difference was 5 points ^[3].
• General-population norms. Norms from 5,018 adults in Germany supported a one-factor structure ^[2].

Validity

• 88% sensitivity for major depression at cutoff ≥10 ^[1]
• 88% specificity for major depression at cutoff ≥10 ^[1]
• Positive predictive value is prevalence-dependent and varies by setting (higher in specialty care, lower in general-population screening)

Reliability

• α = 0.89 Cronbach's alpha (high internal consistency) ^[1]
• r = 0.84 test-retest reliability ^[1]
• ≥5 points as the minimal clinically important difference ^[3]

Limitations

• Screening, not diagnosis: A full clinical evaluation is required to confirm a diagnosis.
• Somatic overlap: Symptoms like fatigue or sleep changes may overlap with physical illnesses.
• Recall bias: Depends on accurate client recall of the past 2 weeks.

Documenting PHQ-9 scores in clinical notes

PHQ-9 scores go in the Objective section of a SOAP note, with severity classification and score change from last session.

Billing the PHQ-9 (CPT 96127)

PHQ-9 administration qualifies for reimbursement under CPT code 96127 (brief emotional/behavioural assessment).

• Unit limit. Medicare's Medically Unlikely Edit caps 96127 at 4 units per date of service; commercial payer limits vary, so confirm your contract.
• One unit per scale. Each unit is one validated scale administered, scored, and documented.
• With the GAD-7. When co-administered with the GAD-7, each scale bills as a separate 96127 unit in the same encounter.

Clinical use cases

Initial screening

Used in primary care, emergency departments, and specialty settings to identify people who may have depression and need further evaluation.

Treatment monitoring

Serial administration tracks symptom changes over time, helping clinicians assess whether interventions are effective or need adjustment.

Research and outcomes

Widely used in clinical trials and quality improvement initiatives to measure depression severity and track outcomes.

Collaborative care

Supports shared decision-making between clients and providers by providing data on symptom patterns and treatment progress.

Chronic disease management

Screens for depression in people with chronic medical conditions (diabetes, heart disease, cancer).

Value-based care

Supports quality metrics for depression screening and treatment response in quality reporting frameworks such as HEDIS and PCMH.

PHQ-9 vs other depression and anxiety scales

Choosing the right assessment tool depends on your clinical goals. Here's how the PHQ-9 compares to other widely used mental health screening tools.

PHQ-9 vs GAD-7: depression vs anxiety

Use the PHQ-9 and GAD-7 together for thorough mental health screening, since depression and anxiety frequently co-occur.

PHQ-9 vs BDI-II: brief vs detailed depression assessment

Choose the PHQ-9 in primary care settings, for population screening, and when you need a quick assessment that aligns with DSM criteria. The BDI-II provides more granular symptom detail for specialty mental health settings.

PHQ-9 vs PHQ-2: full screen vs ultra-brief screen

Many practices use the PHQ-2 for universal screening, then give the full PHQ-9 only to those who screen positive (score ≥3). This reduces burden while maintaining sensitivity.

Quick selection guide

• Primary care: PHQ-9 + GAD-7 for thorough mental health screening.
• Time-constrained: start with the PHQ-2, follow up with the full PHQ-9 if positive.
• Specialty mental health: PHQ-9 for routine monitoring, BDI-II for detailed assessment.

PHQ-9 vs GAD-7 vs PCL-5

When clients present with overlapping depressive and anxiety symptoms, both PHQ-9 and GAD-7 are often co-administered. For combined depression, anxiety, and stress screening in a single questionnaire, the DASS-21 is a useful alternative. For clinical guidance on choosing between overlapping scales and interpreting co-occurring scores, see the PHQ-9 vs GAD-7 vs PCL-5 comparison guide.