Patient Health Questionnaire-9
PHQ-9A 9-item self-report instrument for screening and measuring the severity of depression, based on DSM diagnostic criteria.
Ready-to-cite methods sentence
Reliability & validation
Response anchors
Not at all · Several days · More than half the days · Nearly every day
Known limitations
Validated primarily in primary care settings. A score above 10 warrants clinical follow-up but does not constitute a diagnosis. Item 9 (suicidal ideation) requires clinical judgment independent of total score.
Original citation
Kroenke, K., Spitzer, R. L., Williams, J. B. W. (2001). The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606-613.
https://doi.org/10.1046/j.1525-1497.2001.016009606.xQuestions researchers ask
What does the PHQ-9 measure?
A 9-item self-report instrument for screening and measuring the severity of depression, based on DSM diagnostic criteria.
How many items does the PHQ-9 have?
The Patient Health Questionnaire-9 (PHQ-9) has 9 items.
Is the PHQ-9 free to use?
The PHQ-9 is free to use for non-commercial academic research. You don't need to pay a license fee, but you should always cite the original publication.
Is the PHQ-9 reliable?
Validation studies report Cronbach's α of 0.89, test–retest reliability of 0.84. See the reliability section for the population studied and full statistics.
Who developed the PHQ-9, and how do I cite it?
Kroenke, K., Spitzer, R. L., Williams, J. B. W. (2001). The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606-613. https://doi.org/10.1046/j.1525-1497.2001.016009606.x
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Related scales
Library entry verified January 2024. Metadata is provided for reference; item wording is available inside Folio Surveyor, subject to each instrument's licensing.