PHQ 9 (The Best Depression Test)

What is the PHQ 9?

Developed in 1999, the PHQ 9 is a widely endorsed depression test, that is reliable (Cronbach  0.89, see Kroenke, 2001), well tolerated by patients, and easy to administer, making it an excellent adjunct tool for the clinician’s already busy schedule.  The PHQ 9 is unique in that its role is to detect and measure the severity of depression commonly encountered in clinical settings. The 9 items evaluated with this instrument are similar to the 9 criteria required for a diagnosis of Major Depressive Disorder, as found within the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM – 5)

How to score the PHQ 9?

This depression test reminds the participant to be aware that the following 9 questions pertain to the last 2 weeks. The 9 questions are scored based on a depression symptom frequency ranging from 0 = Not at All, 1 = Several Days, 2 = More than Half the Days, 3 = Nearly Every Day.  A total score is obtained, and it is suggested that a score of 1-4 = no depression, 5-9 = mild depression, 10-14 moderate depression, 15-19 = moderately severe depression, and 20-27 = severe depression.

Upon further analysis, a clinician should strongly consider a diagnosis of major depression if the participant scored points for “Thoughts that you would be better off dead or hurting yourself in some way.” Also, the diagnosis of Major depressive disorder would be strongly considered if 5 or more of the 9 criteria were present for at least “more than half of the days” in the past 2 weeks. Of course, clinical evaluation and correlation is paramount when interpreting any scale or exam score, especially when only partial diagnostic criteria have been met.The PHQ 9 is also considered an excellent tool for measuring treatment response and outcomes.  Once a client has a diagnosis of depression, the clinician has the responsibility to evaluate the treatment response to a selected psychotherapy or psychoactive medication.

Where to find the PHQ 9

 The PHQ- 9 is a free test which may reproduced and distributed without required permission of the core developers (Drs. Robert L. Spitzer, Janet B.W. Williams, Kurt Kroenke) according to its owner, Pfizer, INC.

How long does it take to administer the PHQ 9?

This depression test is usually completed within 2-3 minutes.

How long does it take a clinician to score the PHQ 9?

A seasoned clinician, familiar with this instrument, should be able to tally the score, interpret the sum and analyze the results of this depression test in less than 30 seconds.

When should I utilize a different depression test?

Persons who are suspect of having an underlying cognitive impairment would be better served with another screening tool. This would be especially true when overt symptoms of cognitive decline may impair the participant’s ability to comprehend the meaning of the questions found within the PHQ 9. Furthermore, the participant may not be able to recall the frequency of depressive symptoms with any accuracy, given the prevalence of short-term memory impairment in dementia.

What about the GDS?

The Geriatric Depression Scale is a depression test well suited for elders, however, it should not be used on persons suspected of carrying a diagnosis of dementia.  Compared to the PHQ 9, the GDS is less sensitive and less specific (see Phalen et al, 2010), and it also takes a longer time to administer. If you are at all concerned about a cognitive impairment clouding the validity of a depression diagnosis, then one should go straight to the Cornell Scale for Depression in Dementia (CSDD). The CSDD is a 19 item clinician administered tool that combines the information from the nursing staff with the patient interview which, when combined, improves the sensitivity to 93% with a specificity of 97% (see Kørner et al, 2006). You can find the CSDD here.

What about the PHQ 2?

The PHQ 2 is a depression test consisting of just the first 2 items of the PHQ 9. The PHQ 2 has been shown to have a sensitivity of 79% and a specificity of 86%, for the general category of depressive disorder. The PHQ 2 was also shown to have a sensitivity of 87% and a specificity of 78% in diagnosing MDD (Major depressive disorder) with reference to the structured clinical interview associated with the DSM – IV. The brevity of the PHQ 2 does make this an attractive depression test. The PHQ 2 may also be appropriate for detecting MDD among adolescents. So, what’s not to like?  The problem is one of specificity. Recall that specificity refers to the tests ability to correctly identify those without the disease or in other words, when the person tests positive for the disease, you can be more assured they have this disease. Would you feel comfortable knowing that the test you have chosen may falsely label your client with major depressive disorder? It is often suggested that when the patient scores positive on the PHQ -2, then the clinician should introduce the PHQ -9. Why potentially frustrate your client? For these reasons, the PHQ 9 remains a better choice than the PHQ -2.

The PHQ9 vs. BDI-II  

The Beck Depression inventory second edition or BDI-II, has been a reliable depression test for several decades. The BDI -II depression test is a 21 self-report with multiple choice inventory. The BDI was reworked in 1996, increasing the tool’s psychometric and external validity. The Sensitive of the BDI-II was found to be 81% and the specificity of the test was found to be 92%. A total score > 19 indicates moderate depression and a score > 28 indicates severe depression. The manual of the BDI-II indicates that the tool was not designed as a stand-alone instrument of diagnosis, but rather an instrument that determines the presence of depressive symptoms and also the severity of those depressive symptoms. Unfortunately, the test takes 5-10 minutes to complete, which is considered a disadvantage (nowadays) compared to the PHQ -9.

Concluding thoughts.

The PHQ 9 is a solid choice for identifying depressive disorders. The instrument is easy to administer and easy to score. The PHQ 9 is free of charge and is readily available in over 13 languages. There are no observable drawbacks to this tool other than limiting it to those without a major neurocognitive disorder. There are better tests available in persons suspected of having a dementia diagnosis. Potential client frustrations may occur when a psychiatric practice chooses to utilize the PHQ-2, in turn, the client may screen positive requiring the full administration of the PHQ-9. For the reasons noted above, this author feels the PHQ -9 is currently the depression screening test of choice. For more PMHNP resources, please visit our tool kit page.

Kørner, A., Lauritzen, L., Abelskov, K., Gulmann, N., Marie Brodersen, A., Wedervang-Jensen,  T., & Marie Kjeldgaard, K. (2006). The geriatric depression scale and the Cornell scale for depression in dementia. A validity study. Nordic journal of psychiatry, 60(5), 360        364.

Kroenke, K., Spitzer, R. L., & Williams, J. B. (2001). The phq‐9. Journal of general internal            medicine, 16(9), 606-613.

Phelan, E., Williams, B., Meeker, K., Bonn, K., Frederick, J., LoGerfo, J., & Snowden, M.           (2010). A study of the diagnostic accuracy of the PHQ-9 in primary care elderly. BMC          family practice, 11(1), 63.