Current Treatment Recommendations
GRAPPA published treatment recommendations for PsA in 2009 based on evidence from systematic reviews and consensus of 70 rheumatologists and dermatologists with subspecialty expertise in management of psoriatic disease. The group recommended treatment for all aspects of PsA, including peripheral and axial arthritis, skin and nail disease, enthesitis and dactylitis. NSAIDs were recommended for mild peripheral arthritis and disease-modifying antirheumatic drugs (DMARDs), including sulfasalazine (SSZ), leflunomide, methotrexate (MTX) and cyclosporine, for moderate and severe arthritis. TNFi were recommended as second-line treatment after failure of at least one DMARD, but could be considered as first-line therapy in those with poor prognostic indicators (including polyarticular disease, elevated erythrocyte sedimentation rate (ESR) and radiographic damage). NSAIDs, physiotherapy and sacroiliac joint injection were recommended for mild-to-moderate spinal disease, with TNFi reserved for moderate-to-severe axial involvement. While NSAIDs, physiotherapy and corticosteroid use were recommended for mild enthesitis and DMARDs for moderate disease, there is little evidence to support their use. However, GRAPPA asserts that there is grade A evidence for use of infliximab or etanercept in severe enthesitis. Similarly with dactylitis, grade A evidence exists for use of infliximab, with weaker evidence for NSAID, steroid or DMARD use.
The European League Against Rheumatism (EULAR) published their recommendations for pharmacotherapeutic management of PsA more recently in 2012; however, these only focused on the musculoskeletal manifestations of the disease. Recommendations were based on available evidence and consensus, similar to the processes employed by GRAPPA.
The group devised a treatment algorithm based on disease response, drug toxicity, the presence of adverse prognostic factors (≥5 active joints, or high functional impairment or joint damage) and the pattern of arthritis (peripheral joints, axial disease and/or enthesitis). Treatment targets were remission, defined as the absence of signs and symptoms, or at least low disease activity. NSAIDs were considered first line and DMARDs as second line, with MTX favored in patients with significant psoriasis and joint disease. In enthesitis and/or dactylitis, or axial disease that has failed to respond to NSAID treatment, TNFi should be considered. The EULAR group suggested that TNFi use should also be considered despite DMARD naivety in those with poor prognostic indicators (as listed above), but acknowledged that this recommendation is eminence rather than evidence based. Failure of a TNFi merits switching to another TNFi.
The EULAR treatment recommendations also highlight areas for future research, including delineating subpopulations of PsA patients who would benefit from specific DMARD medications, identifying DMARDs that work synergistically in combination, developing a PsA-specific tool to measure disease activity, and the need for treatment targets to be defined. This article will explore many of these issues.