Timing of OMERACT core domain measurement in gout clinical trials: a systematic review of randomised trials.
AIMS: The Outcome Measures in Rheumatology (OMERACT) initiative has endorsed core domain sets for gout trials. The aims of this study were to evaluate the time points and frequencies at which the gout core domains are measured in existing gout urate-lowering therapy and gout flare trials, and whether all collected measurements were reported. METHODS: Urate-lowering therapy (n = 29) and gout flare randomised clinical trials (n = 14) from 2005 were identified from a prior systematic review of core domain reporting. Data were extracted for the time points and frequencies at which each core domain was measured, as well as whether all collected measurements were reported. RESULTS: In urate-lowering therapy trials, the core domains were measured at seven different frequencies. Serum urate and gout flares were most commonly measured monthly, and tophus burden was most commonly measured three monthly. Reporting of all collected measurements varied, from 24/29 (83%) trials for serum urate to 0/2 (0%) trials for activity limitation. In gout flare trials, core domains were measured at nine different frequencies. Pain, joint tenderness and joint swelling were most commonly measured monthly. Reporting of all collected measurements varied, from 13/14 (93%) trials for pain to 3/8 (37.5%) trials for joint tenderness. CONCLUSION: In both urate-lowering therapy and gout flare trials, there is substantial variability in when the core domains are measured, and reporting of collected measurements is inconsistent. This work provides the foundation for a consensus process to establish standardised time points and frequencies for measuring the OMERACT-endorsed gout core domains.