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The PHQ-9

Validity of a brief depression severity measure

Journal of General Internal Medicine volume 16, pages 606–613 (2001)Cite this article

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 “0” (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.

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References

  1. Mulrow CD, Williams JW, Gerety MB, Ramirez G, Montiel OM, Kerber C. Case-finding instruments for depression in primary care settings. Ann Intern Med. 1995;122:913–21.

    PubMed  CAS  Google Scholar 

  2. Whooley MA, Avins AL, Miranda J, Browner WS. Case-finding instruments for depression: two questions are as good as many. J Gen Intern Med. 1997;12:439–45.

    PubMed  Article  CAS  Google Scholar 

  3. Keller MB, Kocsis JH, Thase ME, et al. Maintenance phase efficacy of sertraline for chronic depression: a randomized controlled trial. JAMA. 1998;280:1665–72.

    PubMed  Article  CAS  Google Scholar 

  4. McDowell I, Kristjansson E, Newell C. Depression. In: McDowell I, Newell C, eds. Measuring Health: A Guide to Rating Scales and Questionnaires. 2nd ed. New York, NY: Oxford University Press; 1996:238–86.

    Google Scholar 

  5. Spitzer RL, Kroenke K, Williams JBW. Patient Health Questionnaire Study Group. Validity and utility of a self-report version of PRIME-MD: the PHQ Primary Care Study. JAMA. 1999;282:1737–44.

    PubMed  Article  CAS  Google Scholar 

  6. Spitzer RL, Williams JBW, Kroenke K, et al. Validity and utility of the Patient Health Questionnaire in assessment of 3000 obstetric-gynecologic patients: the PRIME-MD Patient Health Questionnaire Obstetrics-Gynecology Study. Am J Obstet Gynecol. 2000;183:759–69.

    PubMed  Article  CAS  Google Scholar 

  7. Stewart AL, Hays RD, Ware JE. The MOS Short Form General Health Survey: reliability and validity in a patient population. Med Care. 1988;26:724–32.

    PubMed  Article  CAS  Google Scholar 

  8. Spitzer RL, Williams JBW, Gibbon M, First MB. The structured clinical interview for DSM-III-R (SCID). Arch Gen Psychiatry. 1992;49:624–9.

    PubMed  CAS  Google Scholar 

  9. Spitzer RL, Williams JBW, Kroenke K, et al. Utility of a new procedure for diagnosing mental disorders in primary care: the PRIME-MD 1000 study. JAMA. 1994;272:1749–56.

    PubMed  Article  CAS  Google Scholar 

  10. Sackett DL, Haynes RB, Guyatt GH, Tugwell P. Clinical Epidemiology: A Basic Science for Clinical Medicine. 2nd ed. Boston, MA: Little, Brown and Company; 1991:1–441.

    Google Scholar 

  11. Murphy JM, Berwick DM, Weinstein MC, et al. Performance of screening and diagnostic tests: application of receiver operating characteristic analysis. Arch Gen Psychiatry. 1987;44:550–5.

    PubMed  CAS  Google Scholar 

  12. Pasacreta JV. Measuring depression. In: Frank-Stromborg M, Olsen SJ, eds. Instruments for Clinical Health-Care Research. 2nd Ed. Sudbury, MA: Jones and Bartlett Publishers; 1997:342–630.

    Google Scholar 

  13. Kazis LE, Anderson JJ, Meenan RF. Effect sizes for interpreting changes in health status. Med Care. 1989;27:S178–89.

    PubMed  Article  CAS  Google Scholar 

  14. Berwick DM, Murphy JM, Goldman PA, Ware JE, Barsky AJ, Weinstein MC. Performance of a five-item mental health screening test. Med Care. 1991;29:169–76.

    PubMed  Article  CAS  Google Scholar 

  15. Montgomery SA, Asberg M. A new depression scale designed to be sensitive to change. Br J Psychiatry. 1979;134:382–9.

    PubMed  CAS  Article  Google Scholar 

  16. Davidson J, Turnbull CD, Strickland R, et al. The Montgomery-Asberg Depression Scale: reliability and validity. Acta Psychiatr Scand. 1986;73:544–8.

    PubMed  CAS  Google Scholar 

  17. Lambert MJ, Hatch DR, Kingston MD, et al. Zung, Beck, and Hamilton rating scales as measures of treatment outcome: a meta-analytic comparison. J Consult Clin Psychol. 1986;54:54–9.

    PubMed  Article  CAS  Google Scholar 

  18. Katon W, Robinson P, Von Korff M, et al. A multifaceted intervention to improve treatment of depression in primary care. Arch Gen Psychiatry. 1996;53:924–32.

    PubMed  CAS  Google Scholar 

  19. Katon W, Von Korff M, Lin E, et al. Collaborative management to achieve treatment guidelines: impact on depression in primary care. JAMA. 1995;273:1026–31.

    PubMed  Article  CAS  Google Scholar 

  20. Williams JW, Barrett J, Oxman T, et al. Treatment of dysthymia and minor depression in primary care: a randomized controlled trial in older adults. JAMA. 2000;284:1519–26.

    PubMed  Article  CAS  Google Scholar 

  21. Kroenke K, Taylor-Vaisey A, Dietrich AJ, Oxman TE. Interventions to improve provider diagnosis and treatment of mental disorders in primary care: a critical review of the literature. Psychosomatics. 2000;41:39–52.

    PubMed  CAS  Google Scholar 

  22. Simon GE. Can depression be managed appropriately in primary care? J Clin Psychiatry. 1998;59(suppl 2):3–8.

    PubMed  Google Scholar 

  23. Hunkeler EM, Meresman J, Hargreaves WA, et al. Efficacy of nurse telehealth care and peer support in augmenting treatment of depression in primary care. Arch Fam Med. 2000;9:700–8.

    PubMed  Article  CAS  Google Scholar 

  24. Kobak KA, Taylor LH, Dottl SL, et al. A computer-administered telephone interview to identify mental disorders. JAMA. 1997;278:905–10.

    PubMed  Article  CAS  Google Scholar 

  25. Williams JW, Mulrow CD, Kroenke K, et al. Case-finding for depression improves patient outcomes: results from a randomized trial in primary care. Am J Med. 1999;106:36–43.

    PubMed  Article  Google Scholar 

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Authors and Affiliations

  1. the Regenstrief Institute for Health Care and Department of Medicine, Indiana University, Indianapolis, Ind

    Kurt Kroenke MD

  2. the New York State Psychiatric Institute and Department of Psychiatry, Columbia University, New York, NY

    Robert L. Spitzer MD & Janet B. W. Williams DSW

Authors
  1. Kurt Kroenke MD
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  2. Robert L. Spitzer MD
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  3. Janet B. W. Williams DSW
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Correspondence to Kurt Kroenke MD.

Additional information

The development of the PHQ-9 was underwritten by an educational grant from Pfizer US Pharmaceuticals, New York, NY. PRIME-MD is a trademark of Pfizer Copyright held by Pfizer.

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Kroenke, K., Spitzer, R.L. & Williams, J.B.W. The PHQ-9. J GEN INTERN MED 16, 606–613 (2001). https://doi.org/10.1046/j.1525-1497.2001.016009606.x

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  • DOI: https://doi.org/10.1046/j.1525-1497.2001.016009606.x

Key words

  • depression
  • diagnosis
  • screening
  • psychological tests
  • health status