At what Patient Health Questionnaire-9 (PHQ-9) score is depression considered significant?

Significance of PHQ-9 Score for Depression

A PHQ-9 score of 8 or higher is considered significant for depression, based on validated studies in clinical populations. 1

PHQ-9 Scoring and Clinical Significance

The PHQ-9 is a validated 9-item self-report questionnaire that assesses the presence and severity of depression symptoms according to DSM-IV criteria. The interpretation of scores follows a structured approach:

• Score 1-7: None/mild depressive symptomatology 1

  • Indicates minimal symptoms of depression
  • Patients typically have effective coping skills and access to social support

• Score 8-14: Moderate depressive symptomatology 1

  • Represents clinically significant depression requiring attention
  • Indicates subthreshold depressive symptoms
  • Functional impairment ranges from mild to moderate
  • Consultation with psychology or psychiatry is recommended for diagnostic determination

• Score 15-19: Moderate to severe depressive symptomatology 1, 2

  • Indicates presence of most depressive symptoms
  • Symptoms interfere moderately to markedly with functioning
  • Referral to psychology and/or psychiatry for diagnosis and treatment is recommended

• Score 20-27: Severe depressive symptomatology 1, 2

  • Indicates severe depression requiring immediate intervention
  • Significant functional impairment is present

Evidence Supporting the Cutoff Score

The American Society of Clinical Oncology guideline specifically recommends a cutoff score of 8 based on diagnostic accuracy studies with cancer outpatients, supported by meta-analysis data from Manea et al. 1

While the traditional cutoff for the PHQ-9 was originally set at 10 in general populations 2, more recent evidence supports the lower threshold of 8 for improved sensitivity in detecting clinically significant depression 1.

Special Considerations

• Self-harm assessment: One of the PHQ-9 items assesses thoughts of self-harm. For patients with moderate to severe depression, such thoughts are not uncommon. The frequency and specificity of these thoughts are most important for risk assessment. 1

• Screening approach: A phased screening approach is recommended:

  • First: Identify presence/absence of pertinent history or risk factors
  • Second: Screen with the first two items of PHQ-9 (anhedonia and depressed mood)
  • Third: Complete full PHQ-9 if either of the first two items scores ≥2 1

• Clinical context: When interpreting PHQ-9 scores, consider:

  • Duration of symptoms
  • Associated sociodemographic factors
  • Psychiatric or health comorbidities
  • Social impairments 1

• Cultural sensitivity: Use culturally sensitive assessments when possible and tailor assessment for those with learning disabilities or cognitive impairments 1

Clinical Implications

For patients with a PHQ-9 score ≥8:

• Evaluate for functional impairment 1
• Consider consultation with psychology or psychiatry for diagnostic confirmation 1
• Assess for risk of self-harm, particularly with higher scores 1
• For scores ≥15, referral to psychology and/or psychiatry for diagnosis and treatment is strongly recommended 1

The PHQ-9 has demonstrated strong construct validity, with scores correlating well with other depression measures (r=0.73 with BDI) and showing good sensitivity to change over time, making it valuable for both initial assessment and monitoring treatment response. 3, 4