Outcome assessment in psoriatic arthritis

The wide spectrum of manifestations of psoriatic arthritis (PsA) makes the standardized assessment of the disease difficult. Outcome measures used in clinical trials so far have been borrowed from that used in rheumatoid arthritis. These measures, such as the EULAR response criteria have been shown to perform well in psoriatic peripheral polyarthritis. These measures may however not perform well in PsA presenting predominantly as oligoarthritis, axial arthritis, enthesitis or dactylitis. The Group for Research and Assessment of Psoriasis and PsA along with OMERACT has been actively working towards developing validated and feasible measures for the assessment PsA. The first outcome measures workshop in PsA was held at OMERACT 7, and consensus on core domain set for PsA was obtained at OMERACT 8. Subsequently, a few composite indices for the assessment of PsA have been developed and need validation. This article reviews the challenges inherent in the assessment of PsA, the work done by OMERACT and GRAPPA to date, and the future research agenda.