Consensus recommendations for optimal trial design and reporting of core domains in urate-lowering therapy trials for gout: A Delphi study.

AIMS: To achieve consensus for how the Outcome Measures in Rheumatology (OMERACT) endorsed core domains for "chronic" gout trials should be reported, as well as when they should be measured and reported, in phase 3 or later urate-lowering therapy trials. METHODS: Three rounds of a Delphi survey were completed by two groups: patient research partners and other interest holders. For each of the seven core domains there were two questions: "How should the domain be reported?" and "When should the domain be measured and reported?". The measurement timing question was repeated for two trial durations: '≤6 months duration' and '>6 to ≤12 months duration'. Participants scored items 1-9 (1=not important, 9=critical) Consensus was defined as ≥70% participants from both groups scoring an item 7-9. RESULTS: For "How should the core domain be reported?", all seven core domains had more than one item reach consensus. For serum urate, three items met consensus: 'proportion of patients achieving a pre-specified target serum urate', 'mean serum urate' and 'mean change in serum urate'. For the measurement frequency question, the 'baseline' and 'final visit' time points reached consensus for all seven core domains. For serum urate, the 'monthly' frequency in trials ≤6 months duration and the '3-monthly' frequency in trials >6 to ≤12 months duration reached consensus. CONCLUSION: These recommendations on how and when to report the OMERACT-endorsed core domains in urate-lowering therapy trials address a gap in the current core outcome sets. Adoption of these recommendations should improve consistency and comparability across gout trials.