What score on the Patient Health Questionnaire (PHQ)-9 warrants intervention?

PHQ-9 Score Thresholds for Clinical Intervention

A PHQ-9 score of 8 or higher warrants clinical intervention, with the specific intervention intensity determined by the severity category of the score. 1, 2

PHQ-9 Scoring and Intervention Algorithm

Initial Screening Process

1. Begin with PHQ-2 (first two questions of PHQ-9)
   • If either item scores 2 or higher ("more than half the days" or "nearly every day"), proceed to full PHQ-9 1, 2
   • If both items score 0-1, no further screening needed 1

PHQ-9 Score Interpretation and Recommended Interventions

Score Range	Severity Category	Recommended Intervention
1-7	None/Mild	No intervention required; patient likely has effective coping skills [1]
8-14	Moderate	Seek consultation with psychology/psychiatry; consider low-intensity interventions [1,2]
15-19	Moderately Severe	Referral to psychology/psychiatry for diagnosis and treatment; high-intensity interventions [1,2]
20-27	Severe	Urgent referral for psychiatric evaluation; high-intensity interventions [1,2]

Special Considerations

Self-Harm Risk Assessment

• Item 9 on PHQ-9 assesses thoughts of self-harm
• Never omit this question as it may artificially lower the score and miss critical safety concerns 1, 2
• Any positive response to item 9 requires immediate risk assessment regardless of total score 2
• For patients at risk of harm to self/others: refer for emergency evaluation, facilitate safe environment, and initiate one-to-one observation 1

Evidence Quality and Clinical Context

• The traditional cutoff for PHQ-9 is 10, but the American Society of Clinical Oncology recommends a cutoff of 8 based on studies with cancer outpatients 1
• The PHQ-9 has demonstrated excellent test-retest reliability and strong validity as both a diagnostic and severity measure 3
• A 5-point change on the PHQ-9 represents the minimal clinically important difference for individual patients 3

Intervention Types Based on Severity

• Low-intensity interventions (for moderate symptoms):

  • Guided self-help based on cognitive behavioral therapy
  • Group-based CBT
  • Structured physical activity program
  • Pharmacologic treatment as appropriate 1

• High-intensity interventions (for moderately severe to severe symptoms):

  • Individual psychological therapy with licensed mental health professionals
  • Pharmacologic treatment
  • Relapse prevention strategies 1

Monitoring and Follow-up

• Schedule follow-up within 2 weeks of initiating treatment 2
• Continue regular monitoring on a monthly basis using PHQ-9 2
• Target a 50% reduction in PHQ-9 score or achievement of score <5 (remission) 2
• Research shows PHQ-9 is often underutilized for monitoring treatment response, despite its value in measurement-based care 4

Common Pitfalls to Avoid

• Underutilization of PHQ-9 for ongoing monitoring during treatment 4
• Omitting the self-harm question (item 9) 1, 2
• Relying solely on clinical impression rather than validated measures 2
• Inconsistent follow-up that fails to track treatment response 2, 4

The PHQ-9 has proven to be a responsive, reliable, and valid measure for both diagnosing depression and monitoring treatment outcomes, making it an excellent tool for clinical decision-making 5, 6, 3.