PHQ-9 Depression Scale

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The PHQ-9 is the nine item depression scale of the patient health questionnaire.* It is one of the most validated tools in mental health and can be a powerful tool to assist clinicians with diagnosing depression and monitoring treatment response. The nine items of the PHQ-9 are based directly on the nine diagnostic criteria for major depressive disorder in the DSM-IV.

Note that the AIMS Center is of the opinion that what screening and tracking tool you choose in your setting is less important than that there is one; the important piece is that you have something in place that promotes “treat to target” care – that is, keeping track of patient symptoms and problems and systematically tracking whether or not the treatments are helping. Tracking tools, especially the PHQ9, are one of the easiest ways to do this. The PHQ-9 is rather unique in that it functions as a screening tool, an aid in diagnosis, and as a symptom tracking tool that can help track a patient's overall depression severity as well as track the improvement of specific symptoms with treatment.

Advantages of the PHQ-9

  • Shorter than other depression rating scales
  • Can be administered in person by a clinician, by telephone, or self-administered
  • Facilitates diagnosis of major depression
  • Provides assessment of symptom severity
  • Is well validated and documented in a variety of populations
  • Can be used in adolescents as young as 12 years of age


Research has shown that certain scores on the PHQ-9 are strongly correlated with a subsequent major depression diagnosis. However, not everyone with an elevated PHQ-9 is certain to have major depression. The PHQ-9 is intended as a tool to assist clinicians with identifying and diagnosing depression but is not a substitute for diagnosis by a trained clinician.

PHQ-2 Depression Scale

The Patient Health Questionnaire 2 (PHQ-2) is used by some clinicians and organizations to screen patients for undiagnosed depression. The PHQ-2 consists of the first two questions asked on the PHQ-9. If the patient responds affirmatively to either of the two items on the PHQ-2, the following seven questions on the PHQ-9 are asked. This can be a particularly effective way to screen large groups of people for depression.

Using the PHQ-9 in Primary Care

The PHQ-9 has been mostly validated in primary care environments but has also been used sucessfully in Behavioral Health Centers. It can be self-administered or clinician-administered. At the initial visit for depression care the PHQ-9 is used to assist with diagnosis and identification of problem symptoms. At the follow-up visit, the PHQ-9 is used to measure treatment response and identify specific symptoms that are not responding.

Alternatives to the PHQ-9

Several depression screening instruments have been developed and validated for use in primary care and other settings. Instruments vary by whether they are self- or interviewer-reported and applicable to patients with cognitive or language barriers.

The Geriatric Depression Scale (GDS)
This self-report instrument has been studied in multiple settings. There is a five-item version and a 15-item version of this measure. (The 15-item measure has excellent psychometric properties when compared to a structured diagnostic instrument in a sample of functionally impaired, cognitively intact, community-dwelling primary care patients.)

The Center for Epidemiologic Studies Depression Scale
This is one of the most common instruments applied in community studies and also used in primary care settings.

Cornell Scale for Depression in Dementia
This incorporates both observer and informant based information and is helpful in evaluating cognitively impaired patients for depression.

Children’s Depression Inventory
The Children’s Depression inventory (CDI) is a validated depression screener for kids ages 7 -17. It can be used in both clinical and educational settings.  

*The PHQ-9 is adapted from the Primary Care Evaluation of Mental Disorders (PRIME-MD) developed by Drs. Robert L. Spitzer, Janet B.W. Williams, Kurt Kroenke and colleagues with an educational grant from Pfizer Inc. No permission is required to reproduce, translate, display or distribute the Patient Health Questionnaire (PHQ).