A significant amount of joint damage can occur during the first two years of rheumatoid disease activity, so early diagnosis and treatment can significantly affect a patient’s prognosis. However, diagnosing rheumatoid arthritis can be very challenging, because:
- There is no single physical exam or lab test to decisively diagnose RA.
- RA symptoms often mimic those of other diseases, such as lupus, systemic sclerosis, psoriatic arthritis and polymyalgia rheumatica. (Also, an RA-like illness can occur after many viral infections, particularly parovirus infections.)
Because of these challenges, experts recommend that a diagnostic evaluation be performed by a rheumatologist or a physician who has extensive experience with rheumatologic diseases.
To help doctors make early diagnoses, the American College of Rheumatology and the European League Against Rheumatism collaborated to create the 2010 Rheumatoid Arthritis Classification Criteria. Unlike the previous criteria established in 1987, the 2010 guidelines do not require the presence of rheumatoid nodules, symmetric joint symptoms, or joint erosion that is visible on X-rays or other medical imaging—changes that are typically not seen in early RA.1 The 2010 criteria are described below.2
A total point score of 6 or more indicates rheumatoid arthritis.
|0 Points||1 large Joint|
|2 points||1 to 3 small joints (not including large joints)|
|3 points||4 to 10 small joints (not including large joints)|
|5 points||More than 10 joints, including at least one small joint
|0 points||The person has experienced symptoms for less than 6 weeks|
|1 points||The person has experienced symptoms for 6 weeks or more
|0 points||Negative results: Labs are negative for both anti-citrullinated protein antibodies (called ACPA, typically measured using an anti-CCP antibody test) and rheumatoid factor (RF)|
|2 points||Low positive results: Labs show slightly elevated levels of ACPA or RF|
|3 points||High positive results: Labs show elevated levels of ACPA or RF
|Acute Phase Reactants|
|0 points||Normal C-reactive protein (CRP) and normal erythrocyte sedimentation rate (ESR)|
|1 point||Abnormal CRP or abnormal ESR|
Serology and acute phase reactants are measured using blood samples. Points may be added over time or retrospectively.
People with rheumatoid arthritis usually have several joints with active synovitis symptoms lasting 6 or more weeks. Synovitis is inflammation of a joint’s synovial tissue, and its symptoms can include swelling, redness, warmth, pain, and stiffness, particularly after a long period of rest. These symptoms cannot be explained by another condition, such as osteoarthritis or gout.
There is no single lab test can definitively diagnose rheumatoid arthritis. However, there are several blood tests that may be ordered to detect changes in the body that are indicative of rheumatoid arthritis.
Commonly used blood tests measure the presence of rheumatoid factor (RF), anti-cyclic citrullinated peptide (called ACPA or anti-CCP), and inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). These tests are also used to help diagnose other inflammatory conditions—for example, CRP may be used to diagnose heart disease.
A doctor may order imaging if the patient’s clinical evaluation and lab tests did not provide enough information to diagnose or rule out rheumatoid arthritis. Imaging allows the doctor to see if there is evidence of joint damage.
Ultrasound. This imaging technology is used to detect inflammation of the delicate synovial tissue that encapsulates some joints and tendons. This inflammation, called synovitis, is the hallmark symptom of rheumatoid arthritis. Ultrasound can also detect tenosynovitis in the finger, which some researchers believe to be an early sign of RA.3
Ultrasound is performed using either traditional “b-mode” (gray scale) or power Doppler. While less common and more expensive, power Doppler can detect the flow of blood, allowing a physician to see if the synovial inflammation is active.
In addition to being a helpful diagnostic tool, ultrasound can be used to monitor a patient’s response to treatments (though it is rarely used in clinical practice).
X-Ray. In the early stages of the rheumatoid arthritis, a person may only have soft tissue swelling, which is not detectable on an X-ray, so X-rays are not often used for early diagnosis.
X-rays may be used when the disease has progressed. X-rays can help detect bone damage (erosions) that occurs as a result of long-standing rheumatoid arthritis. They can also detect a narrowing of the joints space, which occurs when cartilage degrades and the bones in the joint get closer together.
Magnetic resonance imaging (MRI). Like ultrasound, MRI can detect inflammation and other changes in the joint’s soft tissue before bone erosion takes place. In addition, an MRI can show bone damage.
The drawback to MRI is that that it is more time consuming and expensive than ultrasound and X-ray. Typically, an MRI is not necessary and only recommended when x-rays and ultrasound have not proven helpful.
Physical Examination and Medical History
The appointment will likely begin with the physician taking a thorough medical history. This will include asking the patient to describe his or her symptoms, such as:
- What joints are affected?
- How would you describe the pain? (such as dull and aching or sharp, constant or intermittent)
- Do you have morning stiffness?
- Have you noticed increased fatigue or weight changes?
- Have you experienced other symptoms besides joint pain?
- When did symptoms begin?
- How have symptoms changed over time?
- What makes the patient feel better or worse? (e.g. exercise)
The history will also include a review of the patient’s:
- Other medical problems
- Previous illnesses and treatments
- Current medications
- Family medical history
During the physical exam, a doctor will evaluate the patient’s general health and then evaluate the joints, looking for signs of joint inflammation. For example, the doctor may measure joints’ range of motion and test joint strength and/or endurance.