Is the Patient Health Questionnaire (PHQ-9) supposed to be used every day?

PHQ-9 Frequency of Administration

No, the PHQ-9 is not designed for daily use—it should be administered at strategic intervals for screening, diagnosis, and monitoring treatment response, not as a daily tracking tool. 1

Appropriate Timing for PHQ-9 Administration

Initial Screening and Diagnosis

• The PHQ-9 assesses symptoms over the past two weeks, making daily administration both impractical and clinically meaningless since the timeframe doesn't change day-to-day 2, 1
• Use the PHQ-9 for initial depression screening at appropriate clinical encounters, such as annual visits, new patient evaluations, or when clinical concern arises 2, 1

Monitoring During Treatment

• For patients in active treatment, repeat the PHQ-9 at 6-month and 12-month intervals following an initial elevated score to assess treatment response 1, 3
• Research shows the mean number of PHQ-9 administrations in the 12 months following an elevated score is only 2.1 in typical primary care, suggesting the tool is actually underutilized for monitoring rather than overused 3
• Patients referred to integrated behavioral health services receive more frequent monitoring (higher than 2.1 administrations per year), but this still represents periodic assessment, not daily use 3

Clinical Context-Specific Timing

• In oncology settings, administer the PHQ-9 at initial diagnosis, at appropriate intervals during treatment, and with changes in disease or treatment status 1
• For patients with chronic depressive symptoms (elevated scores in prior years), slightly more frequent monitoring may be warranted, but this still means every few months, not daily 3

Why Daily Use Is Inappropriate

Psychometric Design Limitations

• The PHQ-9 was validated as a severity measure and screening tool, not a daily symptom tracker 4, 5
• The instrument asks about symptom frequency over a two-week period, with response options ranging from "not at all" to "nearly every day" 2, 1
• Daily administration would create overlapping assessment periods that invalidate the scoring system and interpretation 4

Clinical Utility Concerns

• The PHQ-9 demonstrates good sensitivity to change when used appropriately (pre- to post-treatment with adequate time intervals), but this property is lost with excessive frequency 5
• Measurement-based care has a strong evidence base, but this refers to systematic periodic assessment, not daily tracking 3

Common Pitfalls to Avoid

• Do not use the PHQ-9 as a daily mood diary—it lacks the temporal sensitivity for day-to-day fluctuations and will lead to meaningless data 4
• Avoid screening without a management protocol—ensure you have clear pathways for responding to elevated scores before implementing any screening schedule 1
• Never ignore item 9 (self-harm thoughts) regardless of when you administer the tool—this requires immediate assessment even with low total scores 1, 6
• Do not assume more frequent administration equals better care—the evidence shows primary care clinicians already underutilize the PHQ-9 for appropriate periodic monitoring, suggesting the focus should be on consistent interval-based use rather than daily tracking 3

Practical Monitoring Schedule

For patients with mild symptoms (PHQ-9 score 1-7): Reassess at future routine visits or at 3,6, and 12 months, or during times of personal transition or health status changes 1, 6

For patients with moderate symptoms (PHQ-9 score 8-14): Monitor more closely with repeat assessment every 3-6 months or as clinically indicated during treatment 1

For patients with severe symptoms (PHQ-9 score ≥15): Use the PHQ-9 to track treatment response at clinician-determined intervals (typically every 1-3 months during active treatment adjustment), but coordinate with mental health specialists who may use additional assessment tools 1