Abstract
Objective: Prescribing advice recommends higher doses of allopurinol in tophaceous gout "to accomplish full control of gout and to lower serum uric acid to normal or near-normal levels". The aim of this study was to determine whether outcomes differ between individuals with and without tophi over one year of allopurinol prescribed according to a serum urate target.
Methods: Individual level participant data from two randomised trials of gout were analysed (n=383). Both trials used allopurinol with the treat-to-target strategy and a serum urate target of <0.36mmol/L. The primary outcome was the percentage of participants with serum urate <0.36mmol/L at month 12 in those with and without tophi. Secondary outcomes included absence of gout flares. The percentages with serum urate <0.36mmol/L and the absence of gout flares were compared between those with and without tophi at baseline using the Cochran- Mantel Haenszel test, controlling for study.
Results: Most participants were male, of European ethnicity, and had longstanding gout. Tophi were present in 31% of participants. There was no statistically significant difference in the percentage of participants with serum urate <0.36mmol/L at 12 months between those with and without tophi (70.3 vs 73.6, p=0.76)) nor in the percentage without gout flares in the month prior to month 12 between those with and without tophi (71.4% vs 79.7%; p=0.21).
Conclusion: Despite the higher monosodium urate crystal burden in those with tophi, key gout outcomes including urate-lowering efficacy and absence of gout flares are not different to those without tophi when prescribing allopurinol.