How is a Patient Health Questionnaire-9 (PHQ-9) total score interpreted?

PHQ-9 Score Interpretation

The PHQ-9 total score is interpreted using severity cutoffs where scores of 1-7 indicate none/mild depression, 8-14 indicate moderate depression, 15-19 indicate moderately severe depression, and 20-27 indicate severe depression 1, 2.

Scoring Framework

The PHQ-9 uses a 4-point Likert scale (0 = "not at all," 1 = "several days," 2 = "more than half the days," 3 = "nearly every day") to assess the presence of depressive symptoms over the past 2 weeks 2. The total score ranges from 0 to 27.

Clinical Severity Categories

Based on ASCO guidelines 1, 2, the score ranges correspond to:

• 1-7: None/minimal symptoms of depression; patients typically have effective coping skills and access to social support
• 8-14: Moderate symptomatology with subthreshold depressive symptoms; functional impairment ranges from mild to moderate; seek consultation with psychology or psychiatry for diagnostic determination
• 15-19: Moderately severe symptomatology with most depressive symptoms present; symptoms interfere moderately to markedly with functioning; refer to psychology and/or psychiatry for diagnosis and treatment
• 20-27: Severe symptomatology with majority of depressive symptoms; symptoms markedly interfere with functioning; refer to psychology and/or psychiatry for diagnosis and treatment

Critical Cutoff Considerations

The recommended screening cutoff is ≥8 rather than the traditional ≥10, based on validation studies in cancer outpatients and meta-analytic evidence 2. This lower threshold improves sensitivity for detecting clinically significant depression while maintaining acceptable specificity.

However, recent validation research reveals important nuances:

• The original validation study 3 established cutoffs of 5,10,15, and 20 for mild, moderate, moderately severe, and severe depression respectively, with a score ≥10 showing 88% sensitivity and 88% specificity for major depression
• More recent studies show the optimal cutoff varies by population and setting 4, 5
• In psychiatric inpatient populations, optimal cutoffs may be higher (14.5-15.5) due to comorbid conditions 6

Phased Screening Approach

The guidelines recommend a two-step process 2:

1. Initial screening: Administer the 2-item PHQ-9 (assessing anhedonia and depressed mood)

   • Score 0-1: No further screening needed
   • Score 2-3: Complete remaining 7 items

2. Full assessment: If the 2-item screen is positive, complete all 9 items and calculate total score

This approach reduces burden while maintaining sensitivity, as only 25-30% of patients require the full questionnaire 2.

Essential Clinical Actions by Score Range

For any patient at risk of harm to self or others (regardless of score): Immediate referral for emergency psychiatric evaluation, facilitate safe environment, initiate one-to-one observation, and implement harm-reduction interventions 1, 2.

Score 8-14 (Moderate):

• Identify pertinent history and risk factors (prior mood disorder, comorbid anxiety, substance use, chronic illness, recurrent/advanced disease, social isolation, unemployment, low education)
• Consider low-intensity interventions: individually guided self-help based on CBT, group-based CBT, psychosocial group interventions, structured physical activity programs
• Refer for diagnostic evaluation by mental health professional 2, 1

Score 15-27 (Moderately Severe to Severe):

• Immediate referral to psychology/psychiatry for formal diagnosis and treatment
• Consider high-intensity interventions: individual psychological therapy by licensed professionals using evidence-based manuals (cognitive change, behavioral activation, biobehavioral strategies)
• Pharmacologic treatment as appropriate, informed by adverse effect profiles, drug interactions, prior treatment response, and patient preference 2, 1

Important Caveats

Item 9 (suicidal ideation) requires special attention. The frequency and specificity of self-harm thoughts are more clinically significant than their mere presence. While some clinicians omit this item, doing so artificially lowers scores and weakens predictive validity 2. Patients rarely endorse this item in isolation—it typically occurs with multiple other symptom endorsements 2.

First treat medical causes of depressive symptoms (unrelieved pain, fatigue, delirium from infection or electrolyte imbalance) before attributing symptoms solely to depression 2.

Cultural and linguistic considerations: The PHQ-9 shows differential item functioning across populations, particularly for somatic items (sleep, energy, psychomotor changes) 7, 8. Interpretation may require adjustment in specific populations or settings.

Measurement interpretation: Recent evidence suggests patients may interpret PHQ-9 instructions differently than clinicians intend—many patients complete it based on a combination of symptom frequency and severity rather than frequency alone 9, 10. Despite this, the instrument maintains strong psychometric properties and clinical utility 11.