The PHQ-9: Validity of a brief depression severity measure

Kurt Kroenke, Robert L. Spitzer, Janet B.W. Williams

Research output: Contribution to journalArticle

12270 Scopus citations

Abstract

OBJECTIVE: While considerable attention has focused on improving the detection of depression, assessment of severity is also important in guiding treatment decisions. Therefore, we examined the validity of a brief, new measure of depression severity. MEASUREMENTS: The Patient Health Questionnaire PHQ) is a self-administered version of the PRIME-MD diagnostic instrument for common mental disorders. The PHQ-9 is the depression module, which scores each of the 9 DSM-IV criteria as "O" not at all) to "3" nearly every day). The PHQ-9 was completed by 6,000 patients in 8 primary care clinics and 7 obstetrics-gynecology clinics. Construct validity was assessed using the 20-item Short-Form General Health Survey, self-reported sick days and clinic visits, and symptom-related difficulty. Criterion validity was assessed against an independent structured mental health professional MHP) interview in a sample of 580 patients. RESULTS: As PHQ-9 depression severity increased, there was a substantial decrease in functional status on all 6 SF-20 subscales. Also, symptom-related difficulty, sick days, and health care utilization increased. Using the MHP reinterview as the criterion standard, a PHQ-9 score ≥10 had a sensitivity of 88% and a specificity of 88% for major depression. PHQ-9 scores of 5, 10, 15, and 20 represented mild, moderate, moderately severe, and severe depression, respectively. Results were similar in the primary care and obstetrics-gynecology samples. CONCLUSION: In addition to making criteria-based diagnoses of depressive disorders, the PHQ-9 is also a reliable and valid measure of depression severity. These characteristics plus its brevity make the PHQ-9 a useful clinical and research tool.

Original languageEnglish (US)
Pages (from-to)606-613
Number of pages8
JournalJournal of general internal medicine
Volume16
Issue number9
DOIs
StatePublished - Jan 1 2001

Keywords

  • Depression
  • Diagnosis
  • Health status
  • Psychological tests
  • Screening

ASJC Scopus subject areas

  • Internal Medicine

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