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What Do Patient Health Questionnaires Like PHQ9 Measure?

Sep 29, 2021 / by Holly Wilson

What Do Patient Health Questionnaires Like PHQ9 Measure?

Patient health questionnaires have become a standard mental health assessment tool administered by providers to patients, particularly in care settings that lack sufficient psychiatric care resources. Since patient health questionnaires are so prevalent in assessing mental health, it is important to better understand them. In this blog post, we'll take a closer look at one of the patient health questionnaires most frequently used by providers – the PHQ9 – to explain its history, how it's scored, what it measures, and why its usage may not lead to the most optimal outcomes.

PHQ9: How It Became the "Default" Patient Health Questionnaire

What is the PHQ9? It's an abridged version of the Patient Health Questionnaire (i.e., PHQ) portion of a larger assessment called the PRIME-MD. Let's break this down.

PRIME-MD has two components: a one-page, self-administered patient health questionnaire screener sometimes referred to as the PRIME-MD PHQ and a 12-page clinician evaluation guide (CEG). The PRIME-MD PHQ consists of 26 questions the patient answers to report symptoms of depression, anxiety, alcohol use, somatoform disorder, and eating disorders. The CEG is a structured interview that a clinician uses to follow up on positive responses on the patient questionnaire.

Which brings us back to the PHQ9. In the late 1990s, the nine questions that make up the depression module were broken out from the PRIME-MD PHQ, leading to the creation of the PHQ9. In the decade that followed, the PHQ9 became commonly used by clinicians and researchers and was adopted as a standard measure for depression risk and severity by many organizations.

Then, in 2010, the pharmaceutical company that funded the development of the PRIME-MD and the tools that were derived from it announced that it would make available the PHQ, PHQ9, and other associated assessment scales without copyright restriction and at no cost. Removing the copyright restriction and eliminating fees associated with using the PHQ9 led to the further proliferation and wide use of the PHQ9 by healthcare providers and organizations.

What Does PHQ9 Measure?

We noted that PHQ9 is the depression module of the PRIME-MD, but what does this mean? What does PHQ9 measure?

PHQ9 was designed to screen for depression, measure the severity of symptoms, and measure a patient's response to treatment. It tries to do so by asking patients to speak to how much they have been bothered by nine problems over the previous two weeks. These problems are as follows:

  • Little interest or pleasure in doing things
  • Feeling down, depressed, or hopeless
  • Trouble falling or staying asleep, or sleeping too much
  • Feeling tired or having little energy
  • Poor appetite or overeating
  • Feeling bad about yourself — or that you are a failure or have let yourself or your family down
  • Trouble concentrating on things, such as reading the newspaper or watching television
  • 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
  • Thoughts that you would be better off dead or of hurting yourself in some way

The nine items in the PHQ9 are based on the nine diagnostic criteria for major depressive disorder in the DSM-IV (i.e., DSM-IV: Diagnostic and Statistical Manual of Mental Disorders, fourth edition) published by the American Psychiatric Association (APA) in 1994. Note: The APA has since published the DSM-V.

PHQ9 Scoring: How It's Supposed to Work

Now let's review how the answers provided to these nine items are scored. For their responses, patients can state "not at all," "several days," "more than half the days," or "nearly every day." Each of the nine items can be scored from 0 (for the response of "not at all") to 3 (for the response of "nearly every day"). This means there's a minimum score of 0 and a maximum score of 27. 

Here's one way providers are instructed to interpret PHQ9 scores:

  • For a score of ≤ 4, the diagnosis is "minimal depression," with the score supposed to suggest the patient may not need depression treatment.
  • For a score of 5-9, the diagnosis is "mild depression." For a score of 10-14, the diagnosis is "moderate depression." For the range of 5-14, a physician is supposed to use their clinical judgment about treatment, based on patient's duration of symptoms and functional impairment.
  • For a score of 15-19, the diagnosis is "moderately severe depression." For a score of 20-27, the diagnosis is "severe depression." For a score of >14, this is supposed to warrant treatment for depression, using antidepressant, psychotherapy, and/or a combination of treatment.

Problems with the PHQ9
Did you know that providers misdiagnose major depressive disorder 66% of the time and generalized anxiety disorder 71% of the time?[1]  While not 100% to blame, the PHQ9 is certainly a contributing factor to these shortcomings that can contribute to significant patient health issues. Let's take a closer look at some of the problems associated with the PHQ9 patient health questionnaire.

  • Patient health questionnaires like the PHQ9 are intended to provide guidance to providers as screening tools, but as noted above, providers often rely on PHQ9 scores to make a diagnosis without having a complete picture of the patient’s condition.
  • The problem here is that without considering corresponding comorbidities and disorders (e.g., anxiety, bipolar disease, depression with psychotic features), the provider is unable to make an accurate diagnosis and prescribe the right medication and therapy.
  • When the diagnosis is wrong and/or does not take into consideration these and other critical factors, patient harm can occur.
  • When the PHQ9 and other questionnaires fail to help the provider make an accurate diagnosis, this can delay the care and support mental and behavioral health patients need.
  • The PHQ9 is specifically designed to identify one or more symptoms only for depression. As a result, a practitioner may predetermine a potential diagnosis of depression based upon the tool in use. Such a diagnosis bias can take a patient down a wrong treatment path — one that may not be discovered until there is a serious patient harm event.
  • One of the big appeals of the PHQ9 is that it's easy and fast to use, with completion of the questionnaire usually taking just a few minutes.
  • Since the PHQ9 is free to use and lacks copyright restriction, many software developers have added it to their platforms. This has led many providers to routinely use the screening tool as part of their organization's software without understanding of the shortcomings we've noted.
  • Finally, we come back to the involvement of the large pharmaceutical company. While not problematic on its own, the fact that the PHQ9 was funded by a pharmaceutical company and is often used as a prescribing tool could be viewed as a conflict of interest.

The good news is that while the PHQ9 remains a default option for a patient health questionnaire, it is not the only option. In fact, there are alternatives now in use around the world that are helping healthcare professionals and research organizations better identify, treat, and monitor mental health disorders. To learn more about these options, contact nView today.


[1] 8 Vermani M, Marcus M, Katzman M (2011) Rates of Detection of Mood and Anxiety Disorders in Primary Care: A Descriptive, Cross-Sectional Study. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3184591/, accessed 06/07/2021.

Tags: mental health screeners, mental health assessment, PHQ9

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