The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) Composite Disease Index Project (GRACE)

Abstract

Composite disease outcome measures have been used in rheumatology for some time, but a disease-specific composite measure for psoriatic arthritis has not yet been validated. Currently, instruments developed for use in rheumatoid arthritis are employed in psoriatic arthritis and include the American College of Rheumatology (ACR) response criteria (ACR20, 50, and 70 criteria) and the disease activity score for 28 and 44 joints. However, none of these instruments covers the full spectrum of psoriatic disease and in particular they do not assess the dermatologic contribution. By definition, a composite measure incorporates several dimensions of disease status, often by combining these different domains into a single score, which in the case of psoriatic arthritis should include joints, skin, entheses, dactylitis, and axial disease. Although some indices combine these diverse clinical manifestations of psoriatic disease, the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) established the GRAPPA Composite Exercise (GRACE) project to develop a new index and to compare the existing composite measures.