Outcome Measure
Patient Health Questionnaire 9-Item
What it measures?
- Symptoms of Depression over the previous 2 weeks.
- Symptoms of Depression are based on the 9 criteria for depressive disorders outlined in the Diagnostic and Statistical Manual of Psychological Disorders, 4th Edition (DSM-IV).
- Symptoms assessed include anhedonia, low mood, sleep difficulties, appetite change, self-deprecating thoughts, concentration problems, changes in psychomotor speed, and thoughts of death/self-harm.
- An additional tenth item assesses the degree to which depressive symptoms have resulted in functional impairment.
Who is it for?
Adults aged 18 years +
Instrument Quality
- The PHQ-9 is the most commonly-used screening measure for depression in primary care and has well-established psychometric properties (Moriarty, Gilbody, McMillan & Manea, 2015).
Structure
- 9 items
- 4-point Likert scale
- Respondents indicate how frequently (0 = "Not at all"; 3 = "Nearly every day") they have been bothered by the problems listed in each item (e.g. "Little interest or pleasure in doing things")
Scoring instructions
- Sum item responses to derive the full-scale score.
| Subscale | Item number |
|---|---|
Full-scale (PHQ-9) |
1,2,3,4,5,6,7,8,9 |
Score Interpretation
What higher scores mean?
- More severe depressive symptomatology over the previous 2 weeks., Greater likelihood of meeting criteria for Major Depressive Disorder. A cut-off score of 10 has been identified as the optimal threshold to make a provisional diagnosis of depression across different settings (for meta analyses, see Mitchell, Yadegarfar, Gill & Stubbs, 2016; Moriarty, Gilbody, McMillan & Manea, 2015; Levis, Benedetti & Thombs, 2019).
Identifying risk
A patient may be at risk if they endorse any of the following ‘red flag’ items. Further risk assessment should be undertaken.
| Item number | Item content |
|---|---|
| 9 | Thoughts that you would be better off dead or of hurting yourself in some way |
How to assess symptom severity & change?
| Description | Score Range | |
|---|---|---|
| Normal | 0 | |
| Minimal | 4 | |
| Major Depressive Disorder | >=10 | Provisional Diagnosis |
| Mild | 9 | |
| Moderate | 14 | |
| Moderately Severe | 19 | |
| Severe | 27 |
Instrument developers
- Kroenke K, Spitzer R L, Williams J B (2001). The PHQ-9: validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9): 606-613
Refrences
Levis, B., Benedetti, A., & Thombs, B.D. (2019). Accuracy of Patient Health Questionnaire-9 (PHQ-9) for screening to detect major depression: individual participant data meta-analysis. The BMJ, 365. Mitchell AJ, Yadegarfar M, Gill J, Stubbs B. Case finding and screening clinical utility of the Patient Health Questionnaire (PHQ-9 and PHQ-2) for depression in primary care: a diagnostic meta-analysis of 40 studies. BJPsych Open. 2016 Mar 9;2(2):127-138. doi: 10.1192/bjpo.bp.115.001685. PMID: 27703765; PMCID: PMC4995584. Moriarty AS, Gilbody S, McMillan D, Manea L. Screening and case finding for major depressive disorder using the Patient Health Questionnaire (PHQ-9): a meta-analysis. Gen Hosp Psychiatry. 2015 Nov-Dec;37(6):567-76. doi: 10.1016/j.genhosppsych.2015.06.012. Epub 2015 Jun 18. PMID: 26195347.
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Severity ranges
The ranges developed by Kroenke, Spitzer and Williams (2001) are widely used, and have been shown to distinguish the presence and severity of Major Depressive Disorder
Provisional diagnosis
Multiple systematic reviews and meta-analyses have identified 10 as the optimal cutoff for identifying Major Depressive Disorder (see Levis et al., 2021)
Reliable change and clinically significant improvement
In the original development of the PHQ-9, a 50% decrease, coupled with a post-treatment score below 10 was considered to indicate clinically significant improvement (Kroenke, Spitzer & Williams, 2001). More recent comments by the instrument developer suggest a 5-point decrease and a score below 10 to indicate clinically significant improvement (Kroenke, 2012).
Mean
Standard Deviation
Reliability