PHQ-9

This article describes a module of the Patient Health Questionnaire (PHQ-D) .

PHQ-9

The questionnaire PHQ-9 corresponds to the depression module of the patient health questionnaire ( PHQ-D ) and comprises nine questions on depression. It was developed as a screening instrument for the diagnosis of depression for routine use in the somatic medical field. Unlike many other questionnaires on depression, the PHQ-9 records one of the nine DSM-IV criteria for the diagnosis of "major depression" with each question . The PHQ-9 is recommended by the American Psychiatric Association's DSM-5 Working Group as a tool for measuring the severity of major depression under the new DSM-5 criteria.

Evaluation of the PHQ-9

The PHQ-9 can be evaluated categorically, and the total value can also be interpreted. The interpretation of the total value is used to determine the severity of the depression and can therefore be used in particular to diagnose the course of the disease and to assess the therapeutic effect.

Categorical evaluation

The categorical evaluation is used to diagnose major depression (diagnosis of major depression yes vs no) and is based on the procedure for diagnosing major depression according to DSM-IV. In order to be able to diagnose major depression, a total of 5 of the 9 queried symptoms must be classified as given at least “on more than half of the days”. One of these symptoms must be either lack of interest (Item 13a) or depression (13b). Item i is already considered fulfilled if it is answered with “on individual days”.

Categorical evaluation algorithm for the PHQ-9

syndrome	Items	algorithm
Major Depressive Syndrome	2a-2i	Five or more of questions 2a – i are answered with at least “more than half of the days”; these include question 2a or 2b. (2i is also counted if the answer is “on individual days”.)
Other Depressive Syndromes	2a-2i	Two, three or four of questions 2a – i are answered with at least “more than half of the days”; among these is also a question 2a or 2b. (2i is also counted if the answer is “on individual days”.)

Interpretation of the total value (severity of the depression)

The total scale value “Depressivity” can be calculated using the nine items of the PHQ-9. The answer categories are assigned the following values:

• 0 ("Not at all"),
• 1 ("On individual days"),
• 2 (“On more than half of the days”) and
• 3 ("almost every day")

The scale point value "Depressiveness" thus corresponds to the sum of the point values ​​and lies between 0 and 27. The following interpretation of the possible scale sum values ​​was proposed:

Calculated total scale value	Depression severity
1-4	Minimal depressive symptoms
5-9	Mild depressive symptoms
10-14	Moderate depressive symptoms
15-27	Severe depressive symptoms

Test diagnostic quality criteria

Criterion validity

A meta-analysis with a total of 14 clinical studies (5026 patients in total, 770 of them with major depressive syndrome) showed a high sensitivity of 80% and a specificity of 92% across the studies.

Criterion validity depending on different cut-off values ​​for dimensional evaluation

In a study by the German working group around Bernd Löwe, sensitivities and specificities with different cut-off values ​​were calculated in medical and psychosomatic patients. In addition to the categorical evaluation, cut-off values ​​enable flexible adaptation to the corresponding use of the questionnaire. So u. a. Lower cut-off values ​​are recommended for screening questions than for epidemiological questions. The sensitivities vary in dimensional evaluation depending on the respective cut-off value, for the diagnosis of major depression between 73% and 98% (specificity from 55% to 95%). For the diagnosis of all depressive disorders, sensitivities of 58% to 93% result (specificities of 54% to 92%).

Sensitivity and specificity with categorical evaluation

In a categorical evaluation, the PHQ-9 shows a sensitivity of 78% (psychosomatic patients) and 86% (medical patients) and a corresponding specificity of 80% and 94% for the diagnosis of major depression. For the diagnosis of all depressive disorders, the PHQ-9 has a sensitivity of 78% (psychosomatic patients) or 75% (medical patients) and a specificity of 71% and 90%.

Reliability

The internal consistency for the PHQ-9 turned out to be very good with Cronbach's . and the test-retest reliability is also very good. ${\displaystyle \alpha =0.88}$ ${\displaystyle \alpha =0.89}$

The PHQ-9 has also been validated as a telephone interview and shows good values.

Change sensitivity

The PHQ-9 shows good change sensitivity when using the sum value, so that it can also be used in longitudinal studies, e.g. B. for measuring therapy effects can be used.

Comparative values

Within the German validation study by Gräfe et al. sum values ​​of the PHQ-9 were examined more closely in 357 general medical / internal medicine patients and 171 psychosomatic patients. Patients with major depression (according to SKID) had an average total depression score of M = 17.9 (SD 4.5). In contrast, the total value for patients with all depressive disorders was M = 11.7 (SD = 5.0) and for patients without depressive disorders M = 5.9 (SD = 4.2) For comparison, the average total depression value in the normal population is 3.6 (SD = 4.08) .

Evaluation example

To clarify the evaluation, the following table shows a case study for diagnosing a major depression and for calculating the sum of the scale value “depression”.

Evaluation example : 43-year-old man who looks sad and complains of fatigue in the last month.

2.	Over the past 2 weeks, how often have you felt affected by the following symptoms?	Not at all	On individual days	More than half the days	Almost every day
a	Little interest or pleasure in what you do				Χ
b	Depression, melancholy, or hopelessness		Χ
c	Difficulty falling or staying asleep, or sleeping too much				Χ
d	Feeling tired or lacking energy				Χ
e	Decreased appetite or an excessive need to eat		Χ
f	Bad opinion of yourself; Feeling like a failure or having let the family down			Χ
G	Difficulty concentrating on something, e.g. B. reading the newspaper or watching TV				Χ
H	Were you moving or speaking so slow that others would notice? Or, on the contrary, were you "fidgety" or restless and thus had a stronger urge to move than usual?	Χ
i	Thoughts that you would rather be dead or feel sorry for yourself		Χ

In this case study, the criteria for Major Depressive Syndrome are met in the PHQ-D, as five of items 2a to 2i are ticked with “On more than half of the days” or “Almost every day” and item 2a is below this. Item 2i, which asks about suicide fantasies, deserves special attention in any case: It is counted - as in the case study - whenever the patient states suicide fantasies (or has ticked something other than “not at all”). The further medical discussion in this patient did not reveal any evidence of a manic episode in the past, or that the symptoms were caused by organic factors or medication or drugs. In addition, the duration and severity of the symptoms went beyond a simple grief reaction. On the basis of the PHQ-D and the medical consultation, the disorder diagnosis of major depression could be made. Further exploration of the suicide fantasies revealed no evidence of acute suicidality. The quantitative evaluation results in a scale point value of 17 for depression, which corresponds to a pronounced degree of severity (one item with point value 0; three items with point value 1; one item with point value 2 and four items with point value 3).

Notes on usage authorization

The PHQ-D and its subscales are freely available and free of charge and can be used for non-commercial purposes without charge. When using the PHQ-D or a short form, the German version of the instrument must be quoted correctly when the data generated is published.

Web links

• uke.de PHQ-9-D questionnaire - PDF

Footnotes

1. ^ Proposed Draft Revisions to DSM Disorders and Criteria. ( Memento from October 19, 2012 in the web archive archive.today )
2. ↑ ^{a b} K. Kroenke, RL Spitzer, JB Williams: The PHQ-9. Validity of a letter depression severity measure. In: J Gen Intern Med. 16, 2001, pp. 606-613.
3. ^ S. Gilbody, D. Richards, S. Brealey, C. Hewitt: Screening for depression in medical settings with the Patient Health Questionnaire (PHQ): a diagnostic meta-analysis. In: J. Gen. Intern. Med. 22, 2007, pp. 1596-1602.
4. ↑ B. Löwe, K. Kroenke, W. Herzog, K. Gräfe: Measuring depression outcome with a brief self-report instrument: Sensitivity to change of the Patient Health Questionnaire (PHQ-9). In: J Affect Disord. 81, 2004, pp. 61-66.
5. ↑ ^{a b c d} K. Gräfe, S. Zipfel, W. Herzog, B. Löwe: Screening of mental disorders with the "health questionnaire for patients (PHQ-D)". Results of the German validation study. In: Diagnostica. 50, 2004, pp. 171-181.
6. ↑ K. Kroenke, RL Spitzer, JB Williams: The PHQ-9. Validity of a letter depression severity measure. In: J Gen Intern Med. 16, 2001, pp. 606-613.
7. ↑ A. Pinto-Meza, A. Serrano-Blanco, MT Penarrubia, E. Blanco, JM Haor: Assessing Depression in Primary Care with PHQ-9. Can it be carried out over the telephone? In: J Gen Intern Med. 20, 2005, pp. 738-742.
8. ↑ B. Leo, J. Unützer, C. Callahan, A. Perkins, K. Kroenke: Monitoring depression outcomes with the PHQ-ninth Responsiveness and reliability. In: Med Care. 42, 2004, pp. 1194-1201.
9. ↑ B. Löwe, K. Kroenke, W. Herzog, K. Gräfe: Measuring depression outcome with a brief self-report instrument: Sensitivity to change of the Patient Health Questionnaire (PHQ-9). In: J Affect Disord. 81, 2004, pp. 61-66.
10. ^ W. Rief, A. Nanke, A. Klaiberg, E. Braehler: Base rates for panic and depression according to the Brief Patient Health Questionnaire: a population-based study. In: Journal of Affective Disorders. 82, 2004, pp. 271-276.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !