Patient Health Questionnaire (PHQ-9)

The Patient Health Questionnaire (PHQ-9) is a multipurpose instrument used for diagnosis, screening, monitoring and measuring the severity of depression. The PHQ-9 is a self-report tool and incorporates the DSM-IV depression diagnostics criteria along with other leading major depressive symptoms. The PHQ-9 uses the frequency of the symptoms which factor into the scoring severity index.

The PHQ-9 also has a clinical utility factor. Since it is a brief tool it is widely used in clinical practice. In a clinical setting, the questionnaire is quickly completed by the patient and then briefly scored by a clinician. The Patient Health Questionnaire (PHQ-9) can also be administered repeatedly, which helps clinicians in tracking improvement or regression of the depressive state of the patient. The PHQ-9 scores of 5, 10, 15, and 20 represent mild, moderate, moderately severe, and severe depression respectably.

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Patient Health Questionnaire (PHQ-9)

Reliability and Validity

The diagnostic validity of the Patient Health Questionnaire (PHQ-9) was established in studies that involved 8 primary care and 7 obstetrical clinics across the United States. The PHQ-9 scores less than or equal to 10 had a sensitivity of 88% and a specificity of 88% for major depression.

In a study looking at the validity of the PHQ-9 in the general population done in 2005 the Patient Health Questionnaire proved to be reliable and valid in not only recognizing major depression but also sub-threshold depressive disorders in the general population.

Administration, Analysis and Reporting

Statistics Solutions consists of a team of professional methodologists and statisticians that can assist the student or professional researcher in administering the survey instrument, collecting the data, conducting the analyses and explaining the results.

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Dissertations that have used the Kessler Psychological Distress Scale

Cheon, Keejeong. 2 May 2012. Psychological Well-Being of Mothers with Preterm Infants. (University of Central Las Angeles).

Alschuler, Kevin. 2006. College Integrated Care: Effectiveness of the Use of Modified Version of the Patient Health Questionnaire for Patients in a University Health Clinic. (Eastern Michigan University).

Seymour, Jennifer M. 2010. The Use of the Beck Depression Inventory – II and the Patient Health Questionnaire-9 with Persons Diagnosed with HIV/AIDS: An Exploratory Study. (University of Toledo).


Kroenke, K., Spitzer R., and Williams W. 2001. The PHQ-: Validity of a Brief Depression Severity Measure.

Martin, Alexandria, Rief, Wilfried, Klaiberg, Antje, and Braehler, Elmar. July 2005. Validity of the Brief Patient Health Questionnaire Mood Scale (PHQ-9) in the General Population. General Hospital Psychiatry 28 (2006).