Depression and anxiety take a devastating toll on patients with rheumatoid arthritis.

Levels of depression and anxiety in rheumatoid arthritis (RA) patients are higher than previously reported and could play an important role in how doctors assess and treat the disease, according to a new study published in the journal Arthritis Care and Research.

Led by researchers at the Arthritis Research U.K. Centre for Genetics and Genomics at the University of Manchester, this study is the first to measure depression in patients with severe, active RA.

Learn How Ultrasound Can Help Treat RA »

Rheumatoid arthritis (RA) is a chronic disease that causes inflammation of the joints, according to the U.S. National Library of Medicine. If not diagnosed and treated right away, the disease can progress and permanently destroy joints and damage vital organs, according to the Arthritis Foundation.

About 1.5 million people in the U.S. have RA, and one-third of the people in the U.S. ages 45 and older with arthritis also suffer from depression or anxiety, according to a 2012 study conducted by researchers at the Centers for Disease Control and Prevention. The disease is most common in women between the ages of 30 and 60, but can also affect men later in life, according to the Arthritis Foundation.

Currently, doctors use a variety of medications to ease symptoms and reduce inflammation in patients with RA. However, no one drug works for each individual and not all patients respond to these drugs.

Therefore, doctors regularly monitor a patient’s level of disease activity with exams and blood tests in order to evaluate how well a treatment is working for that patient, according to the Arthritis Foundation. Doctors also measure disease activity based on how the patient reports feeling before going on biological therapy.

According to an article published in Rheumatology in 2001, depression in RA patients can “interact with the way patients perceive and cope with their physical illness and how they interact with their rheumatologist and general practitioner.”

In the new study, researchers hypothesized that psychological factors, such as mood and beliefs about the illness, influence the way a patient reports feeling before undergoing biological therapy.

To test this theory, the team observed 322 patients with severe RA waiting to go on biological therapy. The team based their study on the 28-joint count disease activity score, called the DAS28, which has become the main criterion for determining how a patient with RA should be treated and whether he or she needs biological therapy. This score includes data on how a patient reports feeling.

“The aim of the study was to see if things like depression and how patients understand the disease affected the different components on the DAS,” said study author Anne Barton, FRCP, Ph.D., in an interview with Healthline. “We found that depression scores did relate to the patient’s assessment of their well-being more than other components of the DAS. However, the surprising finding was how many of the patients had high depression scores.”

These results are important “because without treating the depression, the patient’s DAS28 score might not improve as much as it should on a biological drug, and doctors may assume the drug is ineffective,” said Lis Cordingley, a health psychologist and lead study author.

This study draws attention to the problem of depression in patients with severe RA, Barton said, and may change the way doctors approach treating patients in the future.

For example, the high levels of depression and anxiety found in patients with RA reveal that “routine screening may be appropriate for people awaiting biological therapy,” the study authors wrote.

It also suggests that reporting individual DAS28 components may help doctors more accurately assess the impact of certain therapies on each component of the scale and be able to make adjustments in therapy according to patients’ needs, researchers said.

While these findings better equip doctors to treat RA patients, researchers still have unanswered questions.

“What we still don’t know is whether bringing the inflammation under control with effective treatment improves the depression scores, and that is the focus of our on-going work,” Barton said.