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PHQ-9

Patient Health Questionnaire 9

What is the Patient Health Questionnaire 9 (PHQ 9) and what does it test for?

The Patient Health Questionnaire 9 (PHQ 9), is a self-administered questionnaire in which the patient scores the frequency of their own symptoms over 9 sections between 0 (not at all) and 3 (nearly every day). It is an assessment of depressive symptoms and can be used to make criteria-based diagnosis of depressive disorders. The PHQ 9 can also be used to determine the severity of the depressive symptoms and is particularly sensitive for picking up severe depression. The responses should relate to the patients symptoms over the previous 2 weeks.

The questionnaire does not decipher the origins of a patient’s symptoms, purely the presence, frequency and severity of them. This questionnaire is specific to depressive symptoms and may not be appropriate for those suffering with non-depressive symptoms or acute psychosis.

When should the Patient Health Questionnaire 9 (PHQ 9) be used?

The PHQ 9 has been validated for use in primary care and for research studies. The PHQ 9 should be utilised to ascertain the frequency and severity of depressive symptoms. It can be used as a diagnostic tool, an outcome measure over the course of treatment or to determine appropriate treatment pathways.

The first 2 questions (known as the PHQ 2) can be used alone as a screening tool to determine the presence of any depressive symptoms prior to completing the whole questionnaire. If the first two questions indicate the presence of depressive symptoms then the further 7 questions can be asked. This is often a good way of screening large groups of people quickly. The PHQ 9 can be used from the age of 12 upwards, however there is an adapted adolescent version (known as PHQ A). If a patient is displaying symptoms of other mental health conditions then alternative outcome measurements and assessments should be sought.

How is the Patient Health Questionnaire 9 (PHQ 9) scored?

The questionnaire consists of 9 questions where the patient scores how many days in the last 2 weeks they have experienced certain depressive symptoms. They score 0 (not at all) to 3 (nearly every day). The maximum score is therefore 27 and the minimum score is 0.

Score Interpretation

  • 5-9: Mild
  • 10-14: Moderate
  • 15-19: Moderately Severe
  • 20+ Severe

The Spritzer scoring system defines a diagnosis of severe depression to require a score of 2 or higher on at least 1 of the first two questions (PHQ 2) and then a minimum score of 2 or higher on 5 of the final questions.

PHQ 9 score >10 has a sensitivity of 88% and a specificity of 88% for major depression (Levis, 2019).

Evidence and research supporting the Patient Health Questionnaire 9 (PHQ 9)

The PHQ 9 is widely favoured due to its brevity, sensitivity and specificity. It has been widely researched in many different patient groups with large populations which have verified its validity as a diagnostic tool for severe depression (Spitzer, 1999).

The tool can be shortened into a screening tool using the first 2 questions (PHQ 2) to identify the presence of depressive symptoms but not to diagnose or categorise the severity of depressive symptoms (Kroenke 2003). There is solid research to show that scoring 2 or more in the PHQ 2 correlates to a later diagnosis of depression after completing the further 7 questions (Lowe, 2005; Arroll, 2010).

It has been found that demographics, education and gender of the patient completing the questionnaire can influence the sensitivity (Arroll, 2010). There have been studies showing that the validity of the PHQ 9 remains high when translated to other languages.

What questions does the Patient Health Questionnaire 9 (PHQ 9) ask?

The PHQ 9 covers depressive symptoms only.

Question: Over the last 2 weeks, how often have you been bothered by any of the following problems?

  1. Little interest or pleasure in doing things
  2. Feeling down, depressed or hopeless.
  3. Trouble falling or 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 are a failure and 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

The optional final section of the PHQ 9 covers the functional impact of these symptoms, linking to the quality of life of the patient.

  1. 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?

Each question must be answered by choosing one of the following four weighted answers:

  • Not at all (0)
  • Several days (+1)
  • More than half the days (+2)
  • Nearly every day (+3)

References

  • Kroenke, K., Spitzer, R. And Williams, J. (2001) The PHQ-9. Validity of a brief depression severity measure. Journal of General Internal Medicine. 16(9)
  • Kroenke, K., and Spitzer, R. (2002) The PHQ-9: A new depression diagnostic and severity Measure. Psychiatric Annals. 32(9):509-515.
  • Levis, B., Benedetto, A., and Thomas, B. (2019) Accuracy of Patient Health Questionnaire-9 (PHQ-9) for screening to detect major depression: individual participant data meta-analysis. BMJ. 365:I1476
  • Arroll, B., Goodyear-Smith, F., Crengle, S., et al (2010) Validation of PHQ-2 and PHQ-9 to screen for major depression in the primary care population. Annals of Family Medicine. 8(4):348-353
  • Kroenke, K., Spitzer, R and Williams, J. (2003) The Patient health Questionnaire-2: validity of a two-item depression screener. Med Care. 41(11):1284-1292
  • Spitzer, R., Kroenke, K., Williams J. (1999) Validation and utility of a self-report version of the prime-MD: The PHQ primary care study. Primary Evaluation of Mental Disorders, Patient Health Questionnaire. JAMA. 282(18):1737-1744
  • Lowe, B., Kroenke, K., Grafe, K. (2005) Detecting and monitoring depression with a two-item questionnaire (PHQ-2). Journal of Psychosomatic Research. 58(2):163-171

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