Psoriatic Arthritis

General Principles

Classification

Five major patterns of joint disease occur: (1) asymmetric oligoarticular arthritis, (2) distal interphalangeal joint involvement in association with nail disease, (3) symmetric rheumatoid-like polyarthritis, (4) spondylitis and sacroiliitis, and (5) arthritis mutilans.

Epidemiology

Prevalence varies; however, it has been reported that as many as 30% of patients with psoriasis have some form of inflammatory arthritis.

Treatment

  • NSAIDs, particularly indomethacin, are used to treat the arthritic manifestations of psoriasis in conjunction with appropriate measures for the skin disease.
  • Intra-articular glucocorticoids may be useful in the oligoarticular form of the disease, but injection through a psoriatic plaque should be avoided. Severe skin and joint diseases generally respond well to methotrexate (see Treatment under Rheumatoid Arthritis section).
  • Sulfasalazine and leflunomide may also have disease-modifying effects in polyarthritis.
  • TNF-α blockers may produce dramatic improvement in both skin and joint disease.
  • Ustekinumab is a human monoclonal antibody to the shared p40 subunit of IL-12 and IL-23 that interferes with receptor binding to immune cells. It is administered subcutaneously. In patients who weigh less than 100 kg, the dose is 45 mg SC at week 0 and 4. It is then given every 12 weeks. For patients who weigh more than 100 kg, the dose is 90 mg SC given at the same intervals as the lower dose. It may be administered alone or in combination with methotrexate. Patients should be screened for TB prior to initiating this medication and periodically while on it. Monitor for infections and injection site reactions. Monitor all patients for the development of nonmelanoma skin cancer because this has been reported.
  • Apremilast is an orally administered phosphodiesterase-4 inhibitor. It suppresses multiple proinflammatory cytokines involved in the innate and adaptive immunity. Initial starting dose is 10 mg daily, which is slowly uptitrated to a maximum dose of 30 mg twice daily. GI upset and headaches have commonly been reported.
  • Secukinumab has been approved for psoriasis as well as psoriatic arthritis in the same doses as ankylosing spondylitis (see above).
  • Abatacept and tofacitinib have both been approved for use in psoriatic arthritis (see section Rheumatoid Arthritis).

Complications

Colonization of psoriatic skin with S. aureus increases the risk of wound infection after reconstructive joint surgery.

Outline


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