How is Psoriatic arthritis treated
What principles guide treatment of PsA? What classes of medications can be used to treat the arthritis?
Patients should be treated with similar goal-directed therapy as in other inflammatory arthritides. Remission or sustained low disease activity should be the goal for most patients. Polyarticular disease and an elevated ESR/CRP indicate a worse prognosis. Patients with mild, oligoarticular disease can sometimes be managed with nonsteroidal antiinflammatory drugs (NSAIDs) and intraarticular steroid injections, but in general clinicians should have a low threshold to initiate disease-modifying antirheumatic drugs (DMARDs) or biologic DMARDs. DMARDs should be initiated if NSAIDs fail to control the inflammation, if three or more joints are involved, or if the PASI is >10.
• Methotrexate and leflunomide have been reported to have a small effect on skin involvement, peripheral arthritis, enthesitis, and dactylitis. However, these medications have been shown to neither halt radiographic progression nor effectively treat axial disease or nail disease.
• Anti-TNF α agents with or without methotrexate have been shown to be effective therapy for arthritis, dactylitis, enthesitis, spondylitis, and skin disease. Of note, obesity appears to reduce the effectiveness of anti-TNF agents .
• Ustekinumab (Stelara) is a monoclonal antibody that binds to the p40 subunit common to both IL-12 and IL-23, which prevents cytokine binding to their respective receptors. IL-23 is involved in the differentiation of naïve T cells to Th17 cells, the latter of which is thought important to the pathophysiology of PsA (see Question 17). Ustekinumab is approved for the treatment of both psoriasis and peripheral PsA.
• Secukinumab and Ixekizumab block IL-17 and are effective for treating both skin and musculoskeletal manifestations of PsA.
• Apremilast, an inhibitor of phosphodiesterase 4, also treats both psoriasis and PsA, but magnitude of response is typically less than that of biologic agents.
• Abatacept, an agent that blocks the CD80 and CD86 pathways of T cell costimulation, was recently approved to treat PsA but lacks efficacy in treating psoriasis.
• Tofacitinib, an oral Janus kinase (JAK) inhibitor, was recently approved by the Food and Drug Administration (FDA) after demonstrating efficacy in treating PsA with similar safety profile as in rheumatoid arthritis.
Exacerbation of psoriasis and erythroderma can occur with antimalarials, and consequently some consider them to be contraindicated. Systemic glucocorticoids should also be used cautiously because of the risk of inducing a flare of skin disease if tapered too rapidly. In 2018 the American College of Rheumatology (ACR) released new guidelines for the treatment of PsA that may aid clinicians in the management of patients who are medication-naïve, treatment resistant, or who present with axial or enthesis predominant disease.