Biologic agents in psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic, progressive form of inflammatory arthritis that occurs in individuals with psoriasis. It affects at least 0.3%of the population, although estimates of its prevalence vary widely, and is generally considered an autoimmune disease with unknown antigenic determinants. There currently is no predictive marker indicating which psoriasis patients will develop arthritis (Mease 2004). PsA often is classified as a subtype of spondyloarthropathy, due to shared HLA associations among those with spinal involvement, and characteristic inflammatory clinical and immunopathologic features (Kruithof et al. 2005). Although it is heterogeneous in presentation, this disease often results in significant functional impairment and reduced quality of life (Husted et al. 2001).