Preliminary identification of core domains for outcome studies in psoriatic arthritis using Delphi methods

Objective: To develop a consensus based set of core domains for outcome studies in psoriatic arthritis. Methods: A list of 26 potential domains was prepared through literature review and email discussions amongst the GRAPPA steering committee members and scored by rheumatologists identified through membership of the CASPAR study and the steering committee. Each participant was emailed an up to date review of outcome measures in psoriatic arthritis and asked to distribute 100 points amongst each potential domain. In two subsequent rounds the group median, interquartile range, and earlier responses were emailed to each respondent to provide an opportunity to revise their scoring, Results: Thirty two participants responded to the first round, of whom 30 responded to the third round. For DC-ART, the highest scoring domains were actively inflamed joint count, radiological damage score, patient global assessment, pain, physical function, acute phase response, and quality of life (scores 7 to 12). For SMARD, the highest scoring domains were pain, patient global assessment, physical function, quality of life, and active joint count (scores 10 to 18). For clinical record keeping, three domains scored highly at 10 (pain, patient global assessment, and active joint count). For rehabilitation, the highest scoring domains were physical function quality of 46, pain, patient global assessment, work limitations, and work incapacity (scores 10 to 15). Conclusion: Amongst rheumatologists with an interest in psoriatic arthritis, a reduced list of potential standard outcome domains have been defined by Delphi consensus methods.