Patient Health Questionnaire (PHQ-9)

Evidence Reviewed as of before: 11-01-2011
Author(s): Katie Marvin, MSc PT (Candidate)
Editor(s): Nicol Korner-Bitensky, PhD OT

Purpose

The Patient Health Questionnaire (PHQ-9) is a brief tool used to diagnose and measure severity of depression. The PHQ-9 is shorter than many of the other depression screening instruments and can be self-administered. Adapted from the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV), the PHQ-9 is comprised of the same diagnostic symptom criteria used in the DSM-IV:

  • Two cardinal signs of depression (anhedonia and depressed mood);
  • Cognitions (e.g. guilt/worthlessness and suicidality/thoughts of death); and
  • Physical symptoms (e.g. change in appetite, difficulty sleeping and concentrating, feeling tired/slowed down or restless).

In-Depth Review

Purpose of the measure

The PHQ-9 is a brief tool used to diagnose and measure severity of depression. The PHQ-9 is shorter than many of the other depression screening instruments and can be self-administered. Adapted from the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV), the PHQ-9 includes all 9 diagnostic symptom criteria used in the DSM-IV, including the two cardinal signs of depression: anhedonia and depressed mood. The PHQ-9 is widely used by clinicians and can be used with patients with stroke.

Available versions

The PHQ-9 was developed by Drs. Robert L. Spitzer, Janet W.B. Williams and Kurt Kroenke in 1999.

Features of the measure

Items:

PHQ-9 : Contains the 9 items from the DSM-IV used in the diagnosis of depression. The respondent must recall how often they have experienced the following symptoms over the last two weeks:

  1. Little interest or pleasure in doing things;
  2. Feeling down, depressed or hopeless;
  3. Trouble falling asleep, staying asleep, or sleeping too much;
  4. Feeling tired or having little energy;
  5. Poor appetite or overeating;
  6. Feeling bad about yourself, or that you’re a failure or have let yourself or your family down;
  7. Trouble concentrating on things, such as reading the newspaper or watching television;
  8. Moving or speaking so slowly that other people could have noticed. Or the opposite – being so fidgety or restless that you have been moving around a lot more than usual;
  9. Thoughts that you would be better off dead or of hurting yourself in some way; and
  10. If you indicated any problems, how difficult have those problems made it for you to do your work, take care of things at home, or get along with other people?
    Not difficult at all
    Somewhat difficult
    Very difficult
    Extremely difficult

What to consider before beginning:

Similar to when using other depression screening tools, prior to administration the clinician must rule out physical causes for depression, typical bereavement processes and a history of manic episodes.

Scoring and Score Interpretation:

Each item is evaluated on a severity scale ranging from 0 to 3 where the respondent is asked to rate how often each symptom occurred over the last 2 weeks (0-not at all; 1-several days; 2-more than half of the days or 3-nearly every day), yielding a total score ranging from 0-27. The respondent is also asked how the identified problems have interfered with work, home and/or social life, however responses to this item are not scored or included in the total score.

Score interpretation:

  • 1-4 minimal depression;
  • 5-9 mild depression;
  • 10-14 moderate depression;
  • 15-19 moderately severe depression; and
  • 20-27 severe depression

Time:

The PHQ-9 takes approximately 2-5 minutes to administer.

Training requirements:

The PHQ-9 can be self-administered or clinician administered. No-formal training is required to use the measure.

Equipment:

Only a pencil and the test are needed if the tool is self-administered.

Alternative forms of the PHQ-9

The PHQ-2 is an abbreviated version of the PHQ-9, comprised of the first two questions of the PHQ-9 in which the respondent is asked to rate how often they experience the two cardinal symptoms of depression: anhedonia and depressed mood. PHQ-2 scores range from 0-6. Results from a study by Arroll et al. (2010) suggested that the complete PHQ-9 be administered to respondents scoring ≥ 2 on the PHQ-2; and Williams et al. (2010) suggested the complete PHQ-9 be administered to patients with stroke scoring ≥ 3.

Client suitability

Can be used with:

  • Patients with stroke.
  • The PHQ-9 has also been validated for use with geriatric patients; patients with TBI; in primary care and obstetrics-gynecology settings; and in the general population.

Should not be used with:

  • If self-administered, completion of the PHQ-9 requires that the client have adequate reading comprehension and visual ability. However, in the case of illiteracy or poor vision, the items and possible responses may be read to the respondent.

In what languages is the measure available?

Languages of the measure

The PHQ-9 has been translated into Afrikaans, Arabic, Assamese, Bangla, Bengali, Cantonese, Creole, Czech, Danish, Dutch, Finnish, French, German, Gujarati, Hebrew, Hindi, Hungarian, Italian, Korean, Malayalam, Malaysian Mandarin, Mandarin, Norwegian, Oriya, Polish, Portuguese, Punjabi, Russian, Somali, Spanish, Swedish, Telugu, Tingrinian, Turkish, Urdu and Vietnamese.

These translations can be found at the following website: http://www.phqscreeners.com/

Summary

What does the tool measure? The PHQ-9 measures the severity of depression.
What types of clients can the tool be used for? Can be used with but is not limited to patients with stroke.
Is this a screening or assessment tool? The PHQ-9 has been referred to as both a screening tool and an assessment tool.
Time to administer Approximately 2-5 minutes
Versions The PHQ-9 was developed by Drs. Robert L. Spitzer, Janet W.B. Williams and Kurt Kroenke in 1999. It is intended to be self-administered but can be administered by interview in person or over the telephone.
Other Languages The PHQ-9 has been translated but not necessarily validated in over 35 languages (see PHQ-9 module for complete list).
Measurement Properties
Reliability
  • Two studies examined the internal consistency of the PHQ-9 and reported excellent levels of internal consistency.
  • One study examined the test-retest reliability of the PHQ-9 and reported excellent test-retest.
  • No studies have examined the intra-rater reliability of the PHQ-9.
  • No studies have examined the inter-rater reliability of PHQ-9.
Validity

Construct:

Convergent:

One study reported that the PHQ-9 as excellent correlation with the Beck Depression Inventory (BDI) and General Health Questionnaire (GHQ-12) adequate correlation with the European Quality of Life Questionnaire (EuroQOL); and adequate to excellent correlation with subscales of the Medical Outcomes Study Short Form Health Survey (SF-36).

Floor/Ceiling Effects No studies have examined the floor or ceiling effects of the PHQ-9.
Does the tool detect change in patients? No studies have examined the responsiveness of the PHQ-9 in patients with stroke.
Acceptability PHQ-9 is typically self-administered, however it can be interview-administered in person or by telephone for clients who are unable to self-administer the measure.
Feasibility The measure is brief, simple to score and only the PHQ-9 test sheet and a pencil are required to complete the measure.
How to obtain the tool?

The PHQ-9 can be obtained from:
http://www.phqscreeners.com/

Psychometric Properties

Overview

There is an abundance of research on the psychometric properties of the nine-item Patient Health Questionnaire (PHQ-9). However, little research has been conducted specifically in patients with stroke. For the purposes of this review, we conducted a literature search to identify all relevant publications on the psychometric properties of the PHQ-9. We then selected the original validation and reliability studies as content to be summarized and presented here.

Reliability

The reliability of the PHQ-9 has not been examined in a stroke population.

Internal Consistency:

Kroenke, Spitzer and Williams (2001) investigated the internal reliability of the PHQ-9 in two large studies involving 6,000 participants from primary care and obstetrics-gynecology clinics. Using Cronbach’s alpha, excellent reliability was found in both studies (0.89 and 0.86 respectively).

Test-retest:

Kroenke, Spitzer and Williams (2001) investigated the test-retest reliability of the PHQ-9 in primary care clinics. Excellent test-retest reliability (0.84) was found when the PHQ-9 was administered in clinic and then over the telephone 48 hours later.

Intra-rater:

Not yet examined in a stroke population.

Inter-rater:

Not yet examined in a stroke population.

Validity

To our knowledge, the study by Williams et al. (2005) is the only study to date that has examined the validity of the PHQ-9 in individuals with stroke.

Criterion:

Concurrent:

Not yet examined in a stroke population.

Predictive:

Not yet examined in a stroke population.

Construct:

Convergent/Discriminant:

Martin, Rief, Klaiberg and Braehler (2005) examined the convergent validity of the Brief Beck Depression Inventory (BDI), General Health Questionnaire (GHQ-12), European Quality of Life (EuroQOL) Questionnaire and Medical Outcomes Study Short Form Health Survey (SF-36) with an alternative language version of the PHQ-9, in 2060 participants from the general population. The relationships between the measures were compared using the Welch test. The BDI had excellent correlation with the PHQ-9 (r=.73) and the GHQ-12 and EuroQOL had adequate correlation (r=.59 and r=.50 respectively). The subscales of the SF-36 had adequate to excellent correlation (ranging from r=-.45 to r=-.71).

Known groups.

Not yet examined in a stroke population.

Sensitivity/ Specificity:

Kroenke, Spitzer and Williams (2001) examined the sensitivity and specificity of the PHQ-9 in participants from primary care settings. Mental health professionals (Clinical Psychologists and Psychiatric Social Workers) conducted telephone interviews using the Structured Clinical Interview for Depression (SCID) and PRIME-MD to confirm diagnosis of depression. A PHQ-9 score of ≥10 had excellent sensitivity and specificity for detecting major depression, 88% and 88% respectively.

Williams et al. (2010) examined the sensitivity and specificity of the PHQ-9 and PHQ-2 in 316 patients with stroke. A diagnosis of depression was confirmed using the Structured Clinical Interview for Depression (SCID). A PHQ-9 score of ≥10 was found to have excellent sensitivity and specificity for detecting any severity of depression (78% and 96% respectively) and major depression (91% and 89% respectively). Based on these results, the PHQ-9 should be used as a brief screening measure for assessing depression in patients with stroke.

Responsiveness

To date, the responsiveness of the PHQ-9 has not been examined in a stroke population but has been examined in a group of patients receiving treatment for depression in primary care settings.

Lowe, Unutzer, Callahan, Perkins and Kroenke (2004) examined the responsiveness of the PHQ-9 and the depression scale from the Hopkins Symptom Checklist (SCL-20) in 434 patients receiving treatment for depression in primary care settings (mean age 70.9 years). Standardized effect size scores for the intervals between baseline and 3-months and baseline and 6-months were calculated. Large effect sizes were found for the PHQ-9 and the SCL-20, however the results of this study indicate that PHQ-9 is more responsive. Standardized effect sizes of -1.3 at the 3-month interval and -1.3 at the 6-month interval were found for the PHQ-9; and -0.9 at the 3-month interval and -1.2 at the 6-month interval for the SCL-20.

References

  • Arroll, B., Goodyear-Smith, F., Crengle, S., Gunn, J., Kerse, N. and Fishman, T. et al. (2010). Validation of PHQ-2 and PHQ-9 to screen for major depression in the primary care setting. Annals of Family Medicine, 8, 348-353.
  • Kroenke, K. Spitzer, R.L. & Williams, J.B.W. (2001). Validity of a brief depression severity measure. Journal of General Internal Medicine, 16, 606-613.
  • Martin, A., Rief, W., Klaiberg, A. & Braehler, E. (2005). Validity of the brief Patient Health Questionnaire Mood Scale (PHQ-9) in the general population. General Hospital Psychiatry, 28, 71-77.
  • Williams, L.S., Brizendine, J., Plue, L., Bakas, T., Tu, W. & Hendrie, H. et al. (2005). Performance of the PHQ-9 as a screening tool for depression after stroke. Journal of the American Heart Association, 36, 635-638.

See The Measure

How to obtain the PHQ-9?

The PHQ-9 is available for free for educational and clinical purposes at:
http://www.phqscreeners.com/

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