Measuring Disease Activity in Rheumatoid Arthritis

How do doctors measure disease activity in patients with RA and what do those scores mean?


Most rheumatologists have long relied primarily on their own clinical judgment and intuition when deciding whether a patient with rheumatoid arthritis (RA) requires a change in treatment to keep the disease under control. However, there is now solid evidence that RA patients do best when doctors use a “treat to target” approach – that is, adjusting a patient’s therapy as necessary to achieve a specific goal.

But the treat-to-target philosophy requires information about your disease activity. How can you hit your target unless your doctor knows when to increase a dose or add a drug to your regimen?

In 2012, the American College of Rheumatology (ACR) recommended six tools for the systematic measurement of disease activity in RA. Using these tools consistently can help identify changes that you may not notice and that may escape a physician’s observation, says rheumatologist Salahuddin Kazi, MD, of the Dallas VA Medical Center, a coauthor of the ACR guidelines. Responding to these changes as soon as possible by modifying treatment can help limit the risk for long-term joint damage, says Dr. Kazi.

The sooner you get the right treatment, the less likely you will suffer long-term joint damage, Dr. Kazi points out. Your doctor can’t literally feel your pain, but he or she could help ease it by using formal tools to track your disease activity.

Many Tools Available

While there may be no acknowledged “best” test for measuring disease activity in RA, dozens of methods have been devised. Broadly speaking, these tests fall into three categories:

  • Patient questionnaires. A simple version is the Visual Analog Scale (VAS), which features a horizontal line with the words NO PAIN on the left and WORST PAIN on the right; you make a mark on the line to indicate how you are feeling. Other more detailed questionnaires ask about how much difficulty you have performing daily activities, such as bathing, dressing and climbing in and out of cars.
  • Joint counts. A doctor examines a specific set of joints and tallies how many are swollen and/or tender. The most common of these tests is the DAS28, which generates a “disease activity score” (hence the acronym “DAS”) based on an examination of 28 joints as well as other factors.
  • Lab tests. The most widely used tests to measure markers of body-wide inflammation are erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).

Most of the ACR-approved measurement tools combine one or more of these elements. For example, the DAS28 combines a joint count, lab test (either the ESR or CRP) and a VAS. These data are plugged into a formula, which produces a number between 0 and 10 that reflects how well your RA is controlled. If the number rises over time, a change in treatment is probably in order.

In a British study, researchers followed 111 RA patients. Half of the participants were cared for by physicians who relied on their own observations to determine whether a patient’s arthritis was improving or worsening. The other half saw physicians who used DAS28. Two years later, 65% of the patients tracked with DAS28 were in remission, compared to just 16% of patients in the usual-care group.

Assessment Tools Not Always Used

Most disease-activity measuring tools were designed for use in clinical studies, and they can be time-consuming and complicated to use. Rheumatologist Nathan Wei, MD, of Frederick, Md., occasionally uses the DAS28 in his practice. However, he says, “I spend more time asking patients, ‘How are you doing?’” He’ll then consider what the patient says about his or her condition, the results of lab tests, and an occasional imaging exam to make treatment decisions.

Physician surveys, however, show that rheumatologists in general place a much higher value on joint counts than on patient feedback when formulating treatment plans. Yet, studies show that patient questionnaires—which are easy to use and require no time or effort on behalf of the physician—can be as effective as the DAS28 for monitoring disease activity.

One ACR-endorsed tool, the Routine Assessment of Patient Index Data 3 (RAPID3), asks patients how limited they are in performing specific daily activities, whether they are having sleep or emotional difficulties, and to rate their pain and overall health on a scale of 0 to 10. “The RAPID3 takes about a minute to complete, seconds for a nurse to grade, and then you have a numerical value of how a patient is doing,” says Patricia Daul, RN, executive clinical director at Buffalo Rheumatology.

RA patients at Daul’s clinic are monitored with regular VAS and RAPID3 testing, which she says has improved care. “Sometimes we’re like cheerleaders, trying to keep patients on therapy,” says Daul. When a patient complains that her medication isn’t working, Daul can point to how his or her test scores have improved over time. That’s often all the motivation a patient needs to stay the course.

Clinical Judgment Always First

“There’s no advantage of one tool over another. They all have reasonable evidence of validity,” says University of Arkansas rheumatologist Nasim Khan, MD, who studies methods for measuring disease activity in RA patients. “More and more practices are adopting some objective fashion of documenting RA activity and making decisions based on that,” he says. “That’s a good thing.”

Dr. Kazi says that doctors still need to use their training and clinical judgment when treating RA patients. Yet it’s clear that adding any of the ACR-endorsed tests can help doctors better manage your RA.

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