Non-radiographic axial spondyloarthritis (nr-axSpA) facts
- Non-radiographic spondyloarthritis (nr-axSpA) is a type of inflammatory arthritis that affects mainly the joints in the spine.
- The typical symptoms of nr-axSpA are back pain and morning stiffness.
- Patients with nr-axSpA do not have abnormalities of the sacroiliac joints on standard X-rays, such as those seen in classic ankylosing spondylitis.
- Other symptoms and signs of nr-axSpA include uveitis (inflammation of part of the eye, causing a red painful eye), inflammation in peripheral joints, and inflammation where tendons attach into bone (enthesitis).
- Treatments used for nr-axSpA include exercise, nonsteroidal anti-inflammatory medications (NSAIDs), and biologics such as certolizumab pegol (Cimzia).
What is spondyloarthritis?
Spondyloarthritis is a family of inflammatory arthritis that includes ankylosing spondylitis, reactive arthritis, psoriatic arthritis, juvenile spondyloarthropathy, undifferentiated spondyloarthropathy, and arthritis and spondylitis related to inflammatory bowel disease (Crohn's disease and ulcerative colitis). This family of inflammatory arthritis can be thought of in two general groups: axial spondyloarthritis and peripheral spondyloarthritis. Peripheral spondyloarthritis affects mainly the peripheral joints (knees, ankles, shoulders, wrists, hands, and feet) and the tendons of these joints.
What is axial spondyloarthritis (axSpA)?
When spondyloarthritis mostly affects the spine, it is referred to as axial spondyloarthritis. In other words, it is a type of inflammatory arthritis that predominantly affects the spine. AxSpA can be severe and disabling. AxSpA is further split into two groups, ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA). Usually patients with AS have abnormalities in the sacroiliac joints (spinal joints in the pelvis) on X-rays. These sacroiliac joint abnormalities are part of many sets of diagnostic criteria for AS.
What is the definition of non-radiographic axial spondyloarthritis (nr-axSpA)?
AS has many features in common with nr-axSpA, but patients with nr-axSpA do not have changes of inflammatory arthritis on routine X-rays of their sacroiliac joints or of the spine. So, patients with nr-axSpA may have similar symptoms and blood test results as patients with AS, but they do not have the same abnormalities on X-ray. It is not known at this time if AS and nr-axSpA are two different diseases or if nr-axSpA is an earlier or less severe form of AS. While patients with nr-axSpA do not have abnormalities in their sacroiliac joints seen on X-rays, they often have inflammation in the sacroiliac joints seen on MRI.
What are causes and risk factors for non-radiographic axial spondyloarthritis (nr-axSpA)?
Risk factors for nr-axSpA include uveitis, psoriasis, and inflammatory bowel disease. Carrying the HLA-B27 gene is one of the major risk factors for any type of spondyloarthropathy, including nr-axSpA. However, most people who have the HLA-B27 gene never develop any type of spondyloarthropathy. In fact, the prevalence of the HLA-B27 gene in the U.S. population is about 8%, but only up to 1% of the U.S. population is estimated to have any type of spondyloarthropathy. Typically, nr-axSpA begins in young adults. The peak age of onset is between 20 and 30 years old, and the symptoms usually begin prior to age 40.
What are non-radiographic axial spondyloarthritis (nr-axSpA) symptoms and signs?
Inflammatory back pain is the main symptom of nr-axSpA. Inflammatory back pain causes stiffness that is worse in the morning and improves with activity and as the day progresses. Patients with inflammatory back pain may wake up in the second half of the night from the pain. Pain and swelling in the peripheral joints may also occur, which most commonly affects four or fewer large joints (for example, an ankle and a knee, or a knee and an elbow). Studies have found that patients with nr-axSpA have impaired quality of life due to their symptoms. Symptoms and signs affecting other parts of the body also occur, including uveitis (inflammation of the eye causing a red, painful eye), arthritis of the peripheral joints (such as knees, ankles, and hands), and enthesitis (inflammation where the tendons insert into the bone). For example, a patient with nr-axSpA may have back pain and stiffness and also pain at the back of the heel where the Achilles tendon attaches.
How do doctors diagnose non-radiographic axial spondyloarthritis (nr-axSpA)?
The diagnosis of nr-axSpA is a clinical diagnosis, meaning that no single blood test, X-ray, or MRI can diagnose nr-axSpA. Diagnosis is made by a physician with expertise in evaluating and treating inflammatory arthritis. Rheumatologists are specialists in diagnosing and treating various kinds of inflammatory arthritis, including nr-axSpA. The diagnosis is based on a history, physical exam, and a combination of laboratory and radiographic testing. Laboratory testing usually will include testing for the presence of the HLA-B27 gene, markers of inflammation such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR or sed rate). Radiographic testing may include plain X-rays and sometimes MRIs.
What are treatment options for non-radiographic axial spondyloarthritis (nr-axSpA)?
Treatment for nr-axSpA includes medications and non-medication treatments. The non-medication treatments are a healthy diet, smoking cessation, physical therapy, and exercise. Medication treatments for nr-axSpA include nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (Voltaren), indomethacin (Indocin), and others, steroid injections into joints, and biologics. Biologics that inhibit TNF (tumor necrosis factor alpha) have been proven effective for ankylosing spondylitis. These include etanercept (Enbrel), adalimumab (Humira), infliximab (Remicade), and certolizumab pegol (Cimzia). These medications often treat nr-axSpA. The TNF inhibitor certolizumab pegol (Cimzia) has been specifically studied in nr-axSpA and proven effective and is approved by the FDA for this indication. Secukinumab (Cosentyx) is a biologic that inhibits the cytokine IL-17. Secukinumab (Cosentyx) is FDA approved for ankylosing spondylitis and has been studied in nr-axSpA, as well.
What is the prognosis for non-radiographic axial spondyloarthritis (nr-axSpA)?
There is no known cure for nr-axSpA. Some patients with nr-axSpA may progress to develop ankylosing spondylitis. However, nr-axSpA is a treatable condition, and many patients improve a great deal with treatment. Often the signs and symptoms can be stabilized, and patients can live a full and productive life.
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Ward, M.M., et al. "2019 Update of the American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network Recommendations for the Treatment of Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis." Arthritis & Rheumatology 79.10 (2019): 1599-1613.