Diagnosing Rheumatoid Arthritis & Measuring Disease Activity
Medically reviewed by Dr. C.H. Weaver M.D. Medical Editor 8/17/2018
There is no single test that confirms the diagnosis, and symptoms can vary from person to person and be similar to those of other joint conditions. Establishing the diagnosis early in the course of disease is important, however, because early diagnosis and treatment of RA helps to minimize joint damage.
If you or your doctor suspect that you have RA, you may wish to see a rheumatologist—a physician who specializes in the diagnosis and treatment of arthritis and other diseases of the joints, muscles and bones.
Tests for RA
If you are experiencing symptoms of RA, such as pain, swelling, and stiffness of joints, your doctor may use several different approaches to establish the diagnosis.1
Medical history: It will be helpful for your doctor to know what symptoms you have, how severe the symptoms are, when the symptoms began, and how the symptoms have changed over time. It’s also important for your doctor to know about any medications that you use and any other health conditions that you have. If you have information about your family’s medical history, that can be helpful as well.
Physical Examination: In addition to performing a general physical examination, your doctor will examine the affected joints.
Laboratory tests: Blood tests can identify changes that are characteristic of rheumatoid arthritis. Your doctor may assess some or all of the following:
- Rheumatoid factor (RF): Many people with RA will test positive for an antibody called rheumatoid factor. RF is not a perfect marker of RA, however, because some people with RA test will test negative, and some people without RA will test positive.
- Anti-citrullinated protein antibody (ACPA): This is another antibody that is often present in people with RA. ACPA may be detectable very early in the course of the disease (in some cases, even before symptoms develop).
- Tests for inflammation: RA involves inflammation, and two commonly used tests for inflammation are the erythrocyte sedimentation rate (the “sed rate”) and a test for C-reactive protein (CRP).
- Other tests: Other tests may also be performed, including a test for anemia. Anemia is common in people with RA.
Imaging: Tools such as X-rays, magnetic resonance imaging (MRI) or ultrasound may be used to assess the presence and extent of damage within joints. Early in the course of RA, however, there may be no apparent damage.
Making the Diagnosis
Based on all of the available information, you doctor will decide how likely it is that you have RA and what the optimal approach to treatment and follow-up is.
In 2010, the American College of Rheumatology and the European League Against Rheumatism developed new classification criteria for RA. These criteria are intended to improve the identification of people with early RA. The criteria consider many of the factors described above, including the extent of joint involvement, blood test results, and duration of symptoms.2
In some cases, the initial diagnosis may be uncertain. Additional visits and testing over time may allow for a more definite diagnosis.
Measuring Disease Activity
The more you and your doctor know about your RA, the better you can manage it. Your doctor will regularly monitor your disease activity, which is the term used to refer to ongoing inflammation, symptoms, and/or joint damage. This regular and systematic monitoring is critical to managing the condition. Information about the level of disease activity allows doctors to monitor your response to treatment and to adjust your treatment as needed.
One commonly used measure of disease activity is the DAS28 (Disease Activity Score with 28 joint counts). The DAS28 involves a count of tender and swollen joints, your own assessment of your health, and lab tests to identify inflammation. The lab tests measure the erythrocyte sedimentation rate (ESR) or levels of C-reactive protein (CRP). Other composite measures of RA disease activity are also available.
A newer way to measure disease activity is with the Vectra DA test, which is an innovative blood test that allows doctors to test for several biological markers (or biomarkers) of RA simultaneously. The test must be ordered by a physician. Vectra DA measures the levels of 12 proteins in the blood—biomarkers that have been linked to RA disease activity—and then combines them into a single score (between 1 and 100) that classifies your current level of RA disease activity as “low”, “moderate”, or “high”. The test does not replace a doctor’s evaluation, but it does provide a precise, objective measure of the underlying biology of your RA. Testing with Vectra DA can provide snapshots of your disease activity at specific points in time, which can help you and your doctor to better manage your RA.
1 National Institutes of Health, National Institute of Arthritis and Musculoskeletal and Skin Disease. Handout on Health: Rheumatoid Arthritis. Last revised April 2009.
2 Aletaha D, Neogi T, Silman AJ et al. 2010 Rheumatoid Arthritis Classification Criteria: An American College of Rheumatology/European League Against Rheumatism Collaborative Initiative. Arthritis & Rheumatism. 2010;62:2569-2581.