What is psoriatic arthritis?
Psoriatic arthritis is an autoimmune disorder characterized by inflammation of the joints, and occasionally the spine. It typically affects 6–10% of psoriasis patients, although the incidence has been estimated to be higher (around 20–40%) in patients with more extensive skin disease. The majority of patients have psoriasis at the onset of their arthritic symptoms, but some may develop skin disease well after the arthritis has presented. Some patients with psoriatic arthritis may never develop psoriasis, but they may have a family history of psoriasis or psoriatic arthritis.
What are symptoms of psoriatic arthritis?
Patients with psoriatic arthritis typically present with joint pain, swelling and AM stiffness. Patients may also have inflammatory low back pain, or back pain which improves, rather than worsens, with activity. This is different from mechanical low back pain, which worsens with activity. Enthesopathy, or inflammation at the sites where tendons and ligaments attach to the bone, is another key feature of psoriatic arthritis. Achilles tendonitis and plantar fasciitis are examples of enthesopathy. Dactylitis (“sausage digit”), nail changes, and eye inflammation are also associated with psoriatic arthritis
What are risk factors for developing psoriatic arthritis?
Certain genes have been identified that make individuals more prone to developing disease. Patients with affected family members are at increased risk. Obesity during early adulthood and HIV have also been identified as risk factors. In patients with psoriasis, the severity of psoriasis, the presence of nail pitting and uveitis have been correlated with an increased risk developing psoriatic arthritis.
How is psoriatic arthritis diagnosed?
The diagnosis of psoriatic arthritis is based predominantly on the presence of clinical symptoms, as described above. There are no laboratory tests that are diagnostic of psoriatic arthritis. Patients with psoriatic arthritis typically test negative for rheumatoid arthritis and other autoimmune disorders. However, certain non-specific laboratory abnormalities, such as elevated inflammatory markers (ESR, CRP), may be present. Joint aspiration and joint fluid analysis may be helpful in establishing the presence of joint inflammation, and ruling out other causes of inflammatory arthritis (ie. crystalline disease such as gout or pseudogout). The presence of specific x-ray abnormalities may be helpful in making a diagnosis. MRIs, which are more sensitive than x-rays, can be used to image an area of concern if x-rays are normal, but there is still a high level of suspicion for an underlying problem.
How is psoriatic arthritis treated?
Mild arthritis symptoms can be managed with non-steroidal anti-inflammatories (NSAIDs) or local steroid injections into the affected joints. Moderate symptoms are treated with traditional disease-modifying anti-rheumatic drugs (DMARDs), such as sulfasalazine or methotrexate. Otezla (Apremilast) is a newer oral medication that has been approved for treatment of both psoriasis and psoriatic arthritis. Patients with severe disease are often treated with biologic agents, such as anti-tumor necrosis factor inhibitors (anti-TNFs) (Etanercept, Remicade, Humira, Cimzia and Simponi), Stelara or Cosentyx. In December 2017, the FDA approved two new medications for psoriatic arthritis: Xeljanz (tofacitinab), an oral medication also used in the treatment of rheumatoid arthritis, and Taltz (Ixekizumab), an injectable biologic.
Are there any useful lifestyle modifications that I can make?
Yes! Several lifestyle modifications have been shown to be beneficial in psoriatic arthritis patients, including weight loss, routine exercise, and avoidance of smoking and excessive ETOH consumption.
Reviewed on July 12, 2018.
Dr. Dee Dee Wu is a rheumatologist who specializes in the treatment of rheumatoid arthritis, psoriatic arthritis, osteoarthritis and osteoporosis. She practices at both the HSS Outpatient Center in Paramus and the hospital’s main campus in New York.