Patient Health Questionnaire 9 (PHQ 9)

What it is

The PHQ 9 is a brief, self administered instrument based on DSM IV criteria for major depression. It is widely used in primary care and medical settings due to its brevity, reliability, and validity. It can be used to screen for depression, support diagnosis, monitor symptoms, and quantify severity.

The PHQ 2 as an initial screen

• Consists of the first two PHQ 9 items: depressed mood and anhedonia.
• Purpose: rapid screen only. Not for diagnosis or longitudinal severity tracking.
• Action: a positive PHQ 2 (commonly a score of 3 or higher) should be followed by the full PHQ 9.

At a glance

• Construct: depressive symptom severity.
• Items: 9 items plus one unscored functional impairment question.
• Time frame: last 2 weeks.
• Scoring: each item 0 (Not at all) to 3 (Nearly every day); total 0 to 27.
• Administration: self administered; takes minutes to complete.
• Availability: free of charge; translations available in many languages.

Scoring and clinical interpretation

Use the sum of the first 9 items for severity. The final functional question is not scored but is essential context for impairment.

Clinical performance and validity

• As screener for major depressive disorder, a cutoff of 10 or higher shows sensitivity about 88 percent and specificity about 88 percent in original validation cohorts.
• Scores of 10 or higher are associated with markedly increased odds of interview diagnosed depression.
• Very low scores (4 or lower) imply a low post test probability for MDD.
• Reliability: excellent internal consistency (Cronbach alpha about .86 to .89 across patient samples).
• Validated across diverse settings and populations, including primary care, obstetrics, older adults, and chronic disease cohorts.

Clinical considerations and nuances

• Screening vs monitoring: the graded severity scale is well suited for tracking response over time.
• Functional question importance: always consider the unscored impairment question when planning care.
• Positive predictive value: meta analyses suggest that in primary care only about half of positive screens ultimately meet MDD criteria after diagnostic interview.
• The PHQ 9 is not a standalone diagnostic instrument. Clinical judgment and a full assessment are required.

Clinical summary

• Use PHQ 2 for rapid screening; if 3 or higher, follow with PHQ 9.
• Use PHQ 9 to measure severity and monitor treatment progress.
• Remember that a cutoff of 10 or higher is a strong indicator but may yield about 50 percent false positives in primary care.
• Always review the functional impairment question and confirm with clinical interview.
• Apply in context of the individual patient and local protocols.

Version and sources

Version: v1.0 — Patient Health Questionnaire 9 (PHQ 9).

Primary sources and key references:

1. Kroenke K, Spitzer RL, Williams JB. The PHQ 9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606-613.
2. Arroll B, Goodyear Smith F, Crengle S, et al. Validation of PHQ 2 and PHQ 9 in primary care. Ann Fam Med. 2010;8(4):348-353.
3. Levis B, Benedetti A, Thombs BD, et al. Accuracy of PHQ 9 for screening to detect major depression: IPD meta analysis. BMJ. 2019;365:l1476.
4. Gilbody S, Richards D, Brealey S, Hewitt C. Screening for depression with the Patient Health Questionnaire: diagnostic meta analysis. J Gen Intern Med. 2007;22(11):1596-1602.