About one-third of the 7.5 million people in America living with psoriasis also have the rheumatic disease psoriatic arthritis (PsA). This is a chronic (ongoing) inflammatory condition that causes pain and stiffness in the joints, typically in the extremities. Among people with PsA, approximately 20 percent will experience PsA of the spine, which may also be called psoriatic spondylitis.
PsA back pain may occur late in the disease’s progression. The primary symptom of PsA of the spine is chronic pain in the lower back and the sacroiliac joints (where the spine and pelvis meet near the hips and buttocks). Inflammatory back pain is different from back pain caused by wear and tear. PsA-related back pain is due to an inflammatory autoimmune response and usually has the following characteristics:
If you have PsA of the spine, you may also have other symptoms of PsA, including joint pain in other areas like your hands and feet on one or both sides of your body. You may notice dactylitis (inflammation in the fingers and toes) and enthesitis (inflammation in the areas where tendons and ligaments connect to bone).
PsA may also cause extra-articular symptoms (not related to the joints), including:
Approximately 15 percent of people with psoriasis may have PsA that’s unrecognized or undiagnosed. Diagnosing PsA, especially in the absence of psoriasis, can be challenging because its symptoms are similar to rheumatoid arthritis, osteoarthritis, gout, and ankylosing spondylitis. People who have PsA and spondylitis may experience back-related symptoms for as many as 10 years before being diagnosed.
Part of the difficulty regarding diagnosis is that there’s no singular test to diagnose PsA. There are also no universally accepted diagnostic criteria for PsA. A dermatologist or rheumatologist is best positioned to determine whether you have PsA and to track how far your condition has progressed. Your doctor will likely take a medical history and perform imaging tests and blood tests to confirm PsA spondylitis or rule out other conditions.
Doctors can sometimes make a PsA diagnosis based on clinical symptoms and by obtaining a family history or personal history. Your doctor will likely ask if you or a family member have previously had psoriatic disease such as PsA or psoriasis. Having a family member who has or has had psoriatic disease is one of the main risk factors for developing PsA. Forty percent of people with PsA have a family history of psoriatic disease. The Spondylitis Association of America reports that if an identical twin has PsA, there is a 75 percent chance that the other twin will have it as well.
A health care provider can use imaging tests such as CT scans, MRI, ultrasounds, and X-rays to detect PsA and any resulting damage to the soft tissues. Imaging tests can also be used to measure the progression of PsA and monitor any damage that may have occurred.
Your doctor may also ask for a blood sample. There are no specific markers in the blood to indicate PsA, but certain proteins in the blood can point to inflammation and help your doctor make an appropriate diagnosis. In particular, your doctor may look for the presence of HLA-B27, a gene that is associated with a higher risk of spinal involvement.
Early diagnosis is important for beginning treatment promptly and preventing long-term, irreversible joint damage. PsA treatment generally aims to manage inflammation and chronic pain and slow or halt disease progression.
Disease-modifying antirheumatic drugs (DMARDs) may sometimes be used as part of your treatment plan to help slow disease progression and prevent lasting joint and tissue damage.
Examples of older DMARDs include:
Biologics, such as tumor necrosis factor (TNF) inhibitors, are another type of DMARD that targets specific proteins that cause inflammation. TNF inhibitors can slow or halt PsA progression in some people. TNF inhibitors include:
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