How often should the Patient Health Questionnaire-9 (PHQ-9) be administered in a patient with depression?

PHQ-9 Administration Frequency in Patients with Depression

The PHQ-9 should be administered at initial diagnosis, at regular intervals during treatment, at 3,6, and 12 months after treatment, at diagnosis of recurrence or progression, and during times of personal transition or reappraisal. 1

Recommended PHQ-9 Administration Schedule

Initial Assessment and Early Treatment Phase

• At initial diagnosis/start of treatment
• Within 2 weeks of starting treatment to assess early response and side effects 2
• Monthly during active treatment phase 2

Maintenance and Follow-up Phase

• At regular intervals during ongoing treatment
• At 3,6, and 12 months after treatment
• At transition points in care (e.g., changing from acute to maintenance phase)

Special Circumstances

• At diagnosis of recurrence or progression of symptoms
• During times of personal transition or reappraisal (e.g., family crisis)
• When approaching significant life changes
• When medication dosages are adjusted 2

PHQ-9 Scoring and Clinical Decision Making

The PHQ-9 provides clinically meaningful scores that guide treatment decisions:

• 5-9: Mild depression
• 10-14: Moderate depression
• 15-19: Moderately severe depression
• ≥20: Severe depression 2

Treatment Response Monitoring

• Target a 50% reduction in PHQ-9 score or achievement of score <5 (remission) 2
• A change of 5 points on the PHQ-9 scale represents the minimal clinically important difference for individual patients 3

Implementation Considerations

Two-Step Screening Approach

1. First screen with the first two items of PHQ-9 (PHQ-2) assessing:
   • Little interest or pleasure in doing things (anhedonia)
   • Feeling down, depressed, or helpless (depressed mood)
2. If either item scores 2 or higher (occurring more than half the time or nearly every day within the last 2 weeks), complete the full PHQ-9 1

Special Attention to Self-Harm Item

• Item 9 on the PHQ-9 assesses thoughts of self-harm
• Positive responses warrant immediate risk assessment
• Do not omit this item as it may artificially lower the score and weaken predictive validity 1

Common Pitfalls to Avoid

• Underutilization: Research shows the PHQ-9 is underutilized for monitoring patients being treated for depression in primary care 4
• Inconsistent follow-up: Failure to administer the PHQ-9 at recommended intervals may miss opportunities to adjust treatment
• Omitting the self-harm question: This weakens the validity of the score and may miss critical safety concerns 1
• Relying solely on clinical impression: The PHQ-9 provides objective measurement of depression severity and treatment response 3

Special Populations

For patients with chronic depression or higher severity symptoms, more frequent monitoring may be beneficial. Patients referred to integrated behavioral health services typically receive more frequent PHQ-9 assessments (average 2.1 assessments in 12 months) 4.

The PHQ-9 has demonstrated excellent responsiveness to treatment with a standardized effect size of -1.85 over 12 weeks of pharmacotherapy, making it an efficient tool for monitoring treatment outcomes 5, 6.