Outcomes of the 2019 GRAPPA workshop on continuous composite indices for the assessment of psoriatic arthritis and membership-recommended next steps

OBJECTIVE: Improving the assessment of psoriatic arthritis (PsA) is a key purpose of the Group for Research and Assessment of Psoriasis and PsA (GRAPPA). Herein, we report the proceedings of the GRAPPA composites workshop at the 2019 GRAPPA annual meeting and the membership's recommended next steps. METHODS: A review of continuous composite measures was conducted in an introductory workshop, followed by 10 breakout group sessions and a final plenary session for feedback and voting. RESULTS: Participants included 154 members: 87 rheumatologists, 18 dermatologists, 2 rheumatologist/dermatologists, 12 patient research partners, 14 academics, 1 methodologist, and 20 industry members. Of voting members, 88.8% agreed a need exists for a continuous composite measure for routine practice, but only 62% were currently using a composite measure. Of these, 27% were using the 28-joint count Disease Activity Score (DAS), which is not a PsA-specific measure; 20% were using a PsA-specific measure such as PsA DAS (PASDAS), Composite Psoriatic Disease Activity Index (CPDAI), or Disease Activity Index for PsA (DAPSA). Members agreed that the existing measures were not feasible in their current forms (CPDAI 83%, PASDAS 82%, and DAPSA 47%) and that modification should be tested. The majority (76%) agreed that disease effect should be measured separately from disease activity. CONCLUSION: The GRAPPA membership supports the need for a continuous composite measure of disease activity for use in routine clinical care, the separate measurement of disease effect and activity, and the testing of modifications to candidate instruments rather than the development of new measures.