What Is the Patient Health Questionnaire-9 (PHQ-9)?

You may have completed the depression screening tool at a recent physical exam or mental health intake appointment. Here’s how it’s used in clinical and research settings.

Learn more about our Clinical Review Process

If you recently had a physical exam with your primary care physician or a mental health intake appointment, you might have filled out a form about depression symptoms. This form is called the Patient Health Questionnaire-9 (PHQ-9), a standardized set of nine questions that help clinicians and researchers assess rates of depression. Below, we delve into how the PHQ-9 is used and scored in research and clinical settings—including Charlie Health’s virtual Intensive Outpatient Program (IOP).

What is the PHQ-9 assessment tool?

As mentioned, the PHQ-9 is a tool used to measure depression rates. It was created in 2001 by several medical doctors using a grant provided by the pharmaceutical company Pfizer. The drug company and developers made the PHQ-9 free and do not require permission to reproduce, display, or distribute the questions. 

Making the screening tool widely accessible meant it could be used across various projects and spaces, simplifying programs and intervention comparisons. It has also been officially translated into more than 30 languages and used in research studies across the world. The PHQ-9 is now the industry standard for depression screening and continues to be translated and adapted for broader use.

There are actually multiple variations of the PHQ-9 used in healthcare settings and research. The two most common variations are the PHQ-8 (the Patient Health Questionnaire-8) and the PHQ-A (the Patient Health Questionnaire-Adolescent).

The PHQ-8 drops the last question of the PHQ-9 scale, which asks about whether or not a respondent has experienced any suicidal ideation. This variation is often used in settings where researchers or staff cannot follow up with a respondent if they indicate that they are suicidal, such as an anonymous survey. 

The PHQ-A is revised to make the language more friendly to youth and young adults. The wording changes in the PHQ-A are subtle when compared to the PHQ-9 but provide additional context that can be helpful for adolescents answering the questions, like asking about schoolwork.

How is the PHQ-9 used for depression screening?

Depression screening is the most common way the PHQ-9 is utilized. Often, patients are asked to fill out the depression screener when they see their primary care physician or during intake appointments with mental health specialists. In these clinical contexts, the PHQ-9 can also be used to improve referral processes and resource allocation for clients who are at risk for depression, research shows.

The PHQ-9 is brief, easy to grasp, and comes with a clear scoring guide for treatment. It prompts people to reflect on their mood over the past two weeks, answering how often they've faced the following specific issues (including a question about suicidality omitted here). Responses include "not at all," "several days," "more than half the days," or "nearly every day," each linked to a score from zero to three, respectively:

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 or 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

A score of less than 10 means a person is probably experiencing minimal to mild depression. A score of 10 to 19 indicates depression symptoms that are typically moderate. A score of more than 20 usually indicates severe depression. Whether your score indicates mild depression, moderate depression, or severe depression, if you’re having thoughts of harming yourself or someone else, this is a mental health emergency, and you should contact The Suicide & Crisis Lifeline by calling or texting 988.

However, none of these scores are a diagnosis of depression or a depressive episode. For a diagnosis, you need to reach out to a healthcare provider. Also, regardless of your depression severity, talking with a professional is recommended if you’re struggling with your mood, mental health, or depression symptoms. 

How is the PHQ-9 used in research?

The PHQ-9 is also a research tool used to calculate rates of depression in studies. It is utilized in studies that investigate the risk factors for developing depression, the path that depression takes, the impact of treatment methods for depression, and other related research topics. 

For example, a study published in late 2022 used the PHQ-9 to measure the efficacy of eating disorder treatment via telemedicine. A 2023 article used the tool to assess depressive symptoms in childhood sexual abuse survivors and offer depression treatment suggestions for this group. Most recently, a study published in early 2024 used the PHQ-A to show that participants with both obsessive-compulsive disorder (OCD) and depression struggled with more severe depressive symptoms than those without OCD. 

In short, if you read a research paper that talks about depression, take a look at the measures section to see what screening tool they used to assess depression in participants—it’s likely the PHQ-9. 

How does Charlie Health use the PHQ-9?

Charlie Health presents the PHQ-9 questions on our intake, discharge, and all post-discharge surveys. These surveys allow us to assess a client's acuity and well-being at intake and track how their symptoms may change through treatment and after they’ve discharged. Whenever you see data or graphics that cite depression symptom improvement within our program, those calculations are based on PHQ-9 scores. Some of our findings based on PHQ-9 (or PHQ-A) scores are as follows:

• Charlie Health’s virtual IOP leads to a 60% reduction in depression symptoms. 
• At discharge, clients’ PHQ-9 depression scores decreased by over 6 points on average, with many clients moving below the clinical cutoff for major depressive disorder.
• Clients with depression reported a simultaneous reduction in symptoms and an improvement in physical health symptoms after receiving holistic care at Charlie Health.

Also, Charlie Health uses PHQ-9 data to assess program quality and improve our industry-leading care by digging into interesting trends and findings within our data. Multiple papers that we’ve published about our programming use the PHQ-9 to assess depression. One of our earliest papers illustrates a significant depression score reduction across our entire clinical population, with a majority of clients falling below the threshold for diagnosed depression by the end of treatment. Another Charlie Health paper examines mental health symptoms in our LGBTQIA+ clients and finds that these clients report significant improvements in depression scores from intake to discharge. 

Depression treatment at Charlie Health 

If you or a loved one are struggling with depression or a depressive episode, Charlie Health is here to help. Charlie Health’s virtual Intensive Outpatient Program (IOP) provides more than once-weekly mental health treatment for young people dealing with complex mental health conditions, including severe, mild, and moderate depression or a depressive disorder like perinatal depression. Our expert clinicians incorporate evidence-based therapies into individual counseling, family therapy, and group sessions. With treatment, managing your depression severity is possible. Fill out the form below or give us a call to start healing today.