How should I administer and interpret the PHQ‑9 questionnaire, and what treatment steps are recommended based on the score?

PHQ-9 Administration and Interpretation

The PHQ-9 should be administered using a phased approach: start with the 2-item version (assessing anhedonia and depressed mood), and only complete the full 9 items if either question scores ≥2; use a cutoff score of 8 (not the traditional 10) to identify clinically significant depression requiring intervention. 1, 2, 1

Administration Protocol

Timing of Screening

Screen patients at these critical junctures 1:

• Initial diagnosis or treatment start
• Regular intervals during active treatment
• 3,6, and 12 months post-treatment
• Disease recurrence or progression
• Times of personal crisis or transition
• When approaching end-of-life care

Phased Screening Approach

Step 1: Risk Assessment Before administering the PHQ-9, immediately assess for harm to self or others. If positive, stop screening and refer emergently to a licensed mental health professional, facilitate a safe environment with one-to-one observation, and initiate harm-reduction interventions 1.

Step 2: Two-Item PHQ-9 (PHQ-2) Administer only these two questions first 1:

1. "Little interest or pleasure in doing things" (anhedonia)
2. "Feeling down, depressed, or helpless" (depressed mood)

Each item is scored 0-3 based on frequency over the past 2 weeks:

• 0 = Not at all
• 1 = Several days
• 2 = More than half the days
• 3 = Nearly every day

If score is 0 or 1 on both items: Stop—no further screening needed 1

If either item scores ≥2: Proceed to Step 3 (approximately 25-30% of patients will need this) 1

Step 3: Complete Remaining 7 Items The remaining items assess 1:

• Sleep problems
• Low energy
• Appetite changes
• Low self-view
• Concentration difficulties
• Motor retardation or agitation
• Thoughts of self-harm

Score Interpretation

Cutoff Scores

Use a cutoff of 8, not 10 1. While the traditional cutoff is 10, evidence from cancer outpatients and meta-analysis supports 8 as more accurate (sensitivity 75-79%, specificity 80-84%) 3, 4.

Severity Categories

• 1-7: None/mild symptomatology
• 8-14: Moderate symptomatology
• 15-19: Moderate to severe symptomatology
• 20-27: Severe symptomatology 1, 2, 5

Treatment Algorithm Based on Score

Score 1-7 (None/Mild)

• No or minimal depressive symptoms
• Patient has adequate coping skills and social support
• Action: No specific intervention required; continue routine monitoring 1, 2

Score 8-14 (Moderate)

• Subthreshold depressive symptoms present
• Functional impairment ranges from mild to moderate
• Action: Refer to psychology or psychiatry for diagnostic determination 1, 2
• Treatment options (low intensity): 1
  • Individually guided self-help or computerized CBT
  • Group-based CBT for depression
  • Structured physical activity program
  • Pharmacologic intervention as appropriate

Score 15-27 (Moderate to Severe/Severe)

• Majority of depressive symptoms present
• Symptoms interfere moderately to markedly with functioning
• May include suicidal ideation
• Action: Immediate referral to psychology and/or psychiatry for diagnosis and treatment 1, 2
• Treatment options (high intensity): 1
  • Individual psychological therapy by licensed mental health professionals using CBT, behavioral activation, biobehavioral strategies
  • Pharmacologic intervention
  • Relapse prevention strategies

Critical Clinical Considerations

Before Treating Depression Symptoms

First address medical causes 1:

• Unrelieved physical symptoms (pain, fatigue)
• Delirium (infection, electrolyte imbalance)
• Other medical contributors

The Self-Harm Item (Item 9)

This item asks about "thoughts that you would be better off dead or hurting yourself" 1. Key points:

• Among patients with moderate-severe depression, such thoughts are common
• Frequency and specificity of thoughts determine actual risk
• Do not omit this item—doing so artificially lowers scores and weakens predictive validity
• Patients rarely endorse this item in isolation; it typically occurs with multiple other symptoms

Monitoring Treatment Response

For patients in treatment, use these benchmarks 6:

• Week 4: PHQ-9 should be <17
• Week 9: PHQ-9 should be <13
• Week 14: PHQ-9 should be <9

A 5-point change represents the minimal clinically important difference for individual patients 7.

Common Pitfalls to Avoid

Interpretation confusion: Patients often complete the PHQ-9 based on a combination of symptom frequency AND severity, while clinicians typically interpret scores as severity alone. This can lead to score misinterpretation 8.

Pain confounding: In patients with chronic pain, items 3,4,5,7,8, and 10 may be problematic as responses are often based on pain-related issues rather than depression, potentially inflating scores 9.

Omitting the suicide item: While tempting to avoid, omitting item 9 weakens the instrument's validity and may cause you to miss patients with more severe symptoms than their score suggests 1.