Do people with tophaceous gout require more allopurinol for good clinical outcomes? Analysis of two randomized controlled trials with allopurinol dose escalation.

Abstract

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. 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. 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). 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.