OBJECTIVE: To describe the ways in which serum urate (SU) and gout flares are reported in clinical trials, and to propose minimum reporting requirements.
METHODS: This analysis was done as part of a systematic review aiming to validate SU as a biomarker for gout. The ways in which SU and flares were reported were extracted from each study by 2 reviewers.
RESULTS: A total of 22 studies (10 randomized controlled trials, 3 open-label extension studies, and 9 observational studies) were identified. There were 3 broad categories of SU reporting: percentage at target SU, mean SU, and change in SU. A median of 2 (range 1-3) categories were reported across all studies. The most common method of reporting SU was percentage at target in 17/22 (77.3%) studies, with all studies reporting a target of SU < 6 mg/dl. There were 12/22 (54.5%) studies reporting mean SU at some time after study entry, with 7 (58.3%) of these reporting at more than just the final study visit. Two ways of reporting gout flares were identified: mean flare rate and percentage of participants with flares. There was variability in time periods over which flares rates were reported.
CONCLUSION: There is inconsistent reporting of SU and flares in gout studies. Reporting the percentage of participants who achieve a target SU reflects international treatment guidelines. SU should also be reported as a continuous variable with a relevant central and dispersion estimate. Gout flares should be reported as both percentage of participants and mean flare rates at each timepoint.