PHQ-9 (or Patient Healthcare Questionnaire 9) is one of the most common tools used to assess Major Depressive Disorder (MDD), a treatable mental illness seen in private practice. The National Institute of Mental Health reported that an estimated 20 million American adults over the age of 18 have experienced at least one depressive episode. That number suggests that at least 8.4% of U.S. adults have presented with depression. With this high prevalence of therapists seeing clients who present with symptoms of depression, it becomes important to understand screening tools for depression.
While several other assessments and screening tools for depression exist, the PHQ-9 is a reliable and valid screening tool that is freely and easily available to therapists. It is a simple and brief tool for clients to use. When therapists use the PHQ-9 in treatment, the tool can help the clinician and client assess for symptoms and severity consistent with a depression diagnosis, develop an appropriate and individualized treatment plan, and evaluate the treatment progress.
What is the PHQ-9?
The PHQ-9 is a self-report screening tool that therapists and clients can use to help diagnose and treat people with Major Depressive Disorder. Providers can also use the PHQ-9 to help support an initial diagnosis as well as during treatment to continue to monitor the severity of symptoms and progress in treatment.
The PHQ-9 consists of nine questions based on the criteria listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM). Clients can independently and easily answer the questions on the tool or the therapist can conduct an interview-type question-and-answer session of the PHQ-9. Each question addresses a symptom of Major Depressive Disorder identified in the DSM. The respondent answers each question on a four-point Likert scale as to the frequency of the various symptoms over the past two weeks. It should take approximately two to five minutes to complete the screening tool and approximately three to five minutes for the clinician to score it.
Providers can freely access the PHQ-9 by going to the website http://www.phqscreeners.com. Users do not need to seek permission or pay to use, administer, reproduce, translate, or distribute the PHQ-9. Additionally, various electronic practice management systems and online telehealth therapy platforms make the PHQ-9 readily available for clinicians to use.
Why use the PHQ-9?
The PHQ-9 can help the treatment provider and client develop a diagnosis, create strong and individualized treatment goals and interventions, and monitor treatment progress. If administered at intake, the therapist can use the information gathered from the PHQ-9 toward assessing a diagnosis of Major Depressive Disorder. The therapist can use the outcome of the PHQ-9 in combination with clinical information and history gathered during the assessment interview process to identify or rule out a diagnosis of Major Depressive Disorder. It is important that the therapist also considers clinical information gathered during the assessment interview rather than assign a diagnosis based solely on the score of the PHQ-9.
Other important information needed to meet the diagnostic criteria of the DSM includes:
- Do the symptoms cause clinically significant distress or impairment (social, occupational, or other)?
- The episode is not related to the effects of a substance or medical condition
- The episode is not better explained by another mental illness
- There is no history of a manic or hypomanic episode
When the therapist administers the PHQ-9 at intake, the outcome gives the clinician and client a clinical picture of the severity of the depression-related symptoms. The clinician can then use this information to assist with developing and designing a more individualized treatment plan for the client.
Administering the PHQ-9 during treatment can provide the therapist and client with information regarding changes in symptom severity. This information can help to assess treatment progress. The clinician can also use the client’s answers on the PHQ-9 to guide a clinical discussion on the treatment progress and to address any need for changes in interventions or a change in the frequency of sessions. For example, if the PHQ-9 administered during treatment indicates an improvement of symptoms, it may be appropriate for the therapist and client to discuss stepping down in the frequency of sessions or continuing with the current treatment model for some time. If the score indicates an increase in the severity of symptoms, then it might warrant a discussion of what to do differently in treatment.
How to administer the PHQ-9
On the PHQ-9, clients answer nine questions on a Likert scale regarding the severity of nine diagnostic criteria identified in the DSM for Major Depressive Disorder over two weeks. Clients can independently answer the questions before the session, during the session, or upon completion of the treatment session. Some clinicians may prefer to administer the tool as part of the treatment session in an interview format. If the therapist administers the PHQ-9 in an interview format, the clinician needs to adhere to the question-and-answer format and not allow for discussion of the questions or responses during the administration time.
Following the completion of the PHQ-9, the treatment session can allow for further discussion of responses, symptoms, and treatment planning based on the answers and overall score. Treatment providers may want to consider administering the tool upon intake, at regular intervals throughout treatment, and again at discharge.
Scoring and interpretation
The PHQ-9 may be completed on paper or by an electronic version.
Clients rate the severity of the listed symptoms over the past 2 weeks according to the answers:
- 0=Not at all
- 1=everal days
- 2 More than half the days
- 3=Nearly every day
The symptoms addressed for measurement in the PHQ-9 include:
- Little interest or pleasure in doing things
- Feeling down, depressed, or hopeless
- Trouble falling asleep or staying asleep, or sleeping too much
- Feeling tired or having little energy
- Poor appetite or overeating
- Feeling bad about yourself, feelings of failure, or having let yourself or your family down
- Trouble concentrating, such as reading the newspaper or watching TV
- Moving or speaking so slowly that other people have noticed. Conversely, being so fidgety or restless that you are moving more than usual
- Thoughts that you would be better off dead, or hurting yourself
A final section asks the respondent “If you checked off any problems, 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?”
The respondent can then answer according to the following choices:
- Not difficult at all (score of 0)
- Somewhat difficult (score of 1)
- Very difficult (score of 2)
- Extremely difficult (score of 3)
Upon the client completing the tool, the clinician totals up the scores to the Likert scale answers.
The total score suggests the severity of depression:
- 1-4 suggests minimal depression
- 5-9 suggests mild depression
- 10-14 suggests moderate depression
- 15-19 suggests moderately severe depression
- A score of 20-27 suggests severe depression
The PHQ-9 is a brief self-administered tool with high reliability and validity that providers and clients can easily use to guide treatment for depression. It is easily administered, scored, and interpreted and can help clinicians with diagnosis, treatment planning, and assessment for treatment progress.
