Psoriatic Arthritis and Back Pain
Your treatment plan may change if PsA affects your spine.
When you think of psoriatic arthritis (PsA), you may imagine skin symptoms or the commonly affected joints, like the fingers, knees, ankles or elbows (often called peripheral arthritis). However, for many people with the disease, back pain will likely become a symptom at some point as well.
When the spine is affected, it’s known as axial arthritis or, more commonly, spondylitis. Spondylitis affects the spine and sacroiliac joints, which are located at the bottom of the back.
Up to 50% of people with PsA have axial arthritis. “Most of them will have a mix of peripheral and axial arthritis,” says M. Elaine Husni, MD, MPH, director of the Arthritis & Musculoskeletal Center at the Cleveland Clinic in Ohio. A much smaller percentage of people with PsA can have inflammation primarily in the axial area (axial dominant involvement) without peripheral symptoms.
Axial involvement is usually a late-onset feature of PsA, but not always. And studies show that most PsA patients with spondylitis can have back symptoms for up to 10 years before diagnosis is made.
Other symptoms of PsA that people with axial disease may have include inflammation where ligaments and tendons insert into bones (enthesitis); inflammation of an entire finger or toe (dactylitis or “sausage digit”); skin disease (psoriasis); pitting and lifting of nails from the nailbed; eye inflammation (uveitis); and inflammatory bowel disease (IBD).
Since the treatment for PsA with axial involvement may be different than for PsA with only peripheral symptoms, it is important to know the signs and talk to your doctor about your back pain.
Features of Axial Involvement in PsA
Inflammatory back pain wakes you up in the middle of the night. It gets better with exercise and worse when you are sedentary. Inflammation in your sacroiliac joints cause hip and buttock pain. You may also experience back stiffness that lasts for 30 minutes or longer in the morning.
Dr. Husni explains that inflammatory back pain is different from mechanical back pain that’s considered “run-of-mill” back pain. This type of pain usually starts with a specific event, such as lifting a heavy object or an injury. It gets worse with use, makes it difficult to sleep and may cause pain that travels down the legs to the feet.
In PsA with axial involvement, X-rays or magnetic resonance imaging (MRI) may show erosions and abnormal bone growth between your vertebrae (or backbone). Over time, these growths may cause the joints of your spine to merge, limiting your range of motion. But studies on PsA patients show they are less likely to lose spinal mobility than those with ankylosing spondylitis, a related type of inflammatory arthritis that affects the spine.
Predictors of Axial Involvement
Certain signs may predict axial involvement in PsA. These include having the HLA-B27 blood protein, experiencing nail changes, a higher number of damaged joints, a high erythrocyte sedimentation rate (often called sed rate) and longer disease duration. Most PsA patients with spondylitis are diagnosed before age 40, although it can occur later in life. Also, men are more likely to have axial involvement.
“Studies suggest axial PsA may be associated with more aggressive peripheral arthritis,” says Alexis Ogdie, MD, assistant professor of medicine and director of the Penn Psoriatic Arthritis Clinic, University of Pennsylvania in Philadelphia.
Treating Axial PsA
Treatment recommendations for peripheral arthritis released by Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) in 2016 include nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, traditional disease-modifying antirheumatic drugs (DMARDs) and a class of biologics called TNF inhibitors. If you develop spondylitis, your treatment plan may need to change.
GRAPPA’s recommendations for axial PsA include NSAIDs, pain relievers, physical therapy and TNF inhibitors. But other possible treatments include different classes of biologics -- such as IL-12, IL-17 and IL-23 inhibitors -- as well as corticosteroid injections into the sacroiliac joint and bisphosphonates (to treat or prevent osteoporosis). The GRAPPA recommendations advise against the use of traditional DMARDs, IL-6 inhibitors and CD20 inhibitors for PsA with axial involvement.
Dr. Ogdie says it is important to treat axial disease specifically. “The oral disease-modifying drugs like methotrexate don’t work for the spine, so you may have to use a TNF inhibitor first. That’s going to give the best symptomatic improvement but also the best long-term prognosis for the spine joints.”
“The most important thing about axial disease in PsA is detecting it,” says Dr. Ogdie. “When people are diagnosed with PsA the first time they should tell the physician if they are having back or neck pain or stiffness – especially in the morning when they first wake up. The reason is so you can target the treatment appropriately. If you start someone on methotrexate for peripheral disease, you are missing that axial component.”
Another consideration is that some people with PsA (especially women) can have axial disease with no symptoms. So it’s a good idea to talk to your doctor about your spine health at your next checkup even if back pain isn’t a problem.