Measuring Depression with PHQ-9

The Patient Health Questionniare (PHQ-9) is a brief test/assessment which consists of nine items. Each item is scored 0 to 3, providing a 0 to 27 severity score. The PHQ-9 can be used as both a diagnostic module as well as a depression severity score.

Over time, the severity scores have been a particularly popular use of the measures, and are now used much more commonly than the provisional diagnoses. For example, cut-points of 5, 10, 15, and 20 represent mild, moderate, moderately severe and severe levels of depression. Also, a cut-point of 10 or greater is considered a “yellow flag” (i.e., drawing attention to a possible clinically significant condition), while a cut-point of 15 is a “red flag” (i.e., targeting individuals in whom active treatment is probably warranted).

• Scores 0-4: No depression
• Scores 5-9: Mild depression; Watchful waiting; repeat PHQ-9 at follow-up
• Scores 10-14: Moderate depression; Treatment plan, considering counseling, follow-up and/or pharmacotherapy
• Scores 15-19: Moderately severe depression; Active treatment with pharmacotherapy and/or psychotherapy
• Scores 20-27: Severe depression; Immediate initiation of pharmacotherapy and, if severe impairment or poor response to therapy, expedited referral to a mental health specialist for psychotherapy and/or collaborative management

A Major Depressive Syndrome is suggested if:

• Items 1 or 2 are at least, “More than half the days”
• At least five or more of items 1-9 are at least, “More than half the days”
• Item 9 is always counted if it is present at all

Other Depressive Syndrome is suggested if:

• Items 1 or 2 are at least, “More than half the days”
• Two, three, or four of items 1-9 are at least, “More than half the days”
  Item 9 is always counted if it is present at all

The diagnoses of Major Depressive Disorder and Other Depressive Disorder requires ruling out normal bereavement (mild symptoms, duration less than 2 months), a history of a manic episode (Bipolar Disorder) and a physical disorder, medication or other drug as the biological cause of the depressive symptoms.

Additional Clinical Considerations. After making a provisional diagnosis with the PHQ-9, there are additional clinical considerations that may affect decisions about management and treatment.

• Have current symptoms been triggered by psychosocial stressor(s)?
• What is the duration of the current disturbance and has the patient received any treatment for it?
• To what extent are the patient’s symptoms impairing their usual work and activities?
• Is there a history of similar episodes, and were they treated?
• Is there a family history of similar conditions?

The final question on the PHQ-9 asks the patients to report, “How difficult have these problems made it for you to do your work, take care of things at home, or get along with other people?” This single patient-rated difficulty item is not used in calculating any score or diagnosis but rather represents the patient‘s global impression of symptom-related impairment. It may be useful in decisions regarding initiation of or adjustments to treatment since it is strongly associated with both psychiatric symptom severity as well as multiple measures of impairment and health-related quality of life.

A particularly important question is how to assess suicide risk in individuals who answer positively to the 9th question of the PHQ-9.

A particularly important use of any measure is its sensitivity to changes of condition severity over time. This is well-established for the PHQ-9 which is increasingly used as a measure to assess the level of depression severity (for initial treatment decisions) as well as an outcome tool (to monitor treatment response).

The PHQ-9 was developed by Drs. Robert L. Spitzer, Janet B.W. Williams, Kurt Kroenke and colleagues, with an educational grant from Pfizer Inc. The PHQ-9 is in the public domain and no permission is required to reproduce, translate, display or distribute.

References

• Kroenke K, Spitzer RL, Williams JBW. The PHQ-9: Validity of a brief depression severity measure. J Gen Intern Med 2001;16:606-613.
• Kroenke K, Spitzer RL. The PHQ-9: a new depression diagnostic and severity measure. Psychiatric Annals 2002;32:509-521. [also includes validation data on PHQ-8]
• Löwe B, Unutzer J, Callahan CM, Perkins AJ, Kroenke K. Monitoring depression treatment outcomes with the Patient Health Questionnaire-9. Med Care 2004;42:1194-1201
• Kroenke K, Spitzer RL, Williams JBW, Löwe B. The Patient Health Questionnaire somatic, anxiety, and depressive symptom scales: a systematic review. Gen Hosp Psychiatry 2010 (in press).