A new study found that a widely used depression screening questionnaire is accurate for people with and without chronic pain, debunking a common misconception that the screening inflates depression scores for people with chronic pain.

Some clinicians and researchers believed a person with chronic pain might score higher on the eight-item Patient Health Questionnaire, or PHQ-8, because they can't sleep or experience fatigue, which are symptoms of both pain and depression. 

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"Could pain symptoSms artificially inflate depression screening scores among those with chronic pain? It's a reasonable question, but it had not yet been definitively answered," said lead author Jennifer S. De La Rosa, strategy director for the U of A Comprehensive Center for Pain and Addiction and an assistant research professor in the U of A College of Medicine – Tucson's Department of Family and Community Medicine. "Using nationally representative population data, we rigorously evaluated this question and found no evidence to support this long-standing concern."

The paper was published in the Journal of Affective Disorders. 

De La Rosa and her team analyzed data from nearly 32,000 U.S. adults who participated in the 2019 National Health Interview Survey. The team used sophisticated data science techniques to assess measurement invariance – ensuring there was no bias – in the PHQ-8 questionnaire.

When comparing the variance of scores for people with or without chronic pain, the data showed that the screener achieved an excellent level of consistency in both groups.

"Clinicians need to know that a positive depression screening is just as reliable in their patients with chronic pain as patients without chronic pain, and they should not hesitate to offer mental health supports to any patient with unmet mental health needs," De La Rosa said. "These conversations require sensitivity to ensure patients feel supported by these conversations rather than stigmatized.

"Right now, there's a national push underway to address treatment-resistant depression, yet for the vast majority of clinical trials, people with chronic pain are excluded from participating," De La Rosa added. "This study provides robust evidence that there would be no scientific problem with including folks living with chronic pain in depression research to help develop treatments capable of meeting the needs of this uniquely underserved population."

The research underscored the way chronic pain and depression are intertwined, reinforcing De La Rosa's previous research, which found that while 1 in 5 people with chronic pain have depression, more than half of those with clinically significant depression symptoms also have chronic pain.

A follow-up paper showed that adults with chronic pain are more likely to experience anxiety and depression than those without chronic pain, yet they access mental health care at lower rates and are less likely to have their mental health needs met in treatment.

"People with chronic pain are, in fact, the most typical patients living with unmet mental health needs, and they are wildly overrepresented among people with treatment resistant depression," De La Rosa said. "Many of them want to participate in trials. They can benefit just as much as others from inclusion, and, critically, it will improve the real-world effectiveness of the new therapies being developed.

"Now is the time to meaningfully consider the unmet mental health needs of people with chronic pain and prioritize their outcomes within the mental health research, policy and advocacy landscape," she added.

In 2023, approximately 64 million U.S. adults experienced chronic pain, according to the Centers for Disease Control and Prevention.

De La Rosa's co-authors were Greg T. Chism, assistant professor of practice at the College of Information Science, former doctoral student Katherine E. Herder; Chung Jung Mun, associate professor at Arizona State University, and senior author Rachel V. Aaron, associate professor at Johns Hopkins School of Medicine.

The study received support from the National Institutes of Health under award nos. K23HD104934 and K12TR005467-01.