Similar gout flare incidence rates when using once- or twice-daily 0.5 mg colchicine prophylaxis after the start of xanthine oxidase inhibitors

To investigate the potential superiority of colchicine prophylaxis twice daily over once daily in preventing gout flares in the first 6 months after initiating xanthine oxidase inhibitors (XOIs). A retrospective cohort study was conducted in three rheumatology centres in the Netherlands. Gout flare incidence densities were calculated for patients using colchicine once or twice daily in the first 6 months after starting XOIs. The incidence rate ratios (IRRs) between groups were analysed using Poisson regression, adjusted for confounders. The proportion of patients reaching a serum urate of <0.36 mmol/L within the first 6 months was compared between groups. In total, 808 gout patients started XOIs (allopurinol in 99.7%) with colchicine prophylaxis: 192 on twice-daily and 616 on once-daily colchicine 0.5 mg. The incidence densities of gout flares were 3.3 and 2.8 per patient-year, resulting in an IRR of 0.93 [95% confidence interval (CI) 0.80–1.09] for twice-daily compared to once-daily colchicine, adjusted for renal function (estimated glomerular filtration rate), serum urate at baseline, duration of colchicine prophylaxis, C-reactive protein, age, duration of illness, fast dose titration, tophi, gouty bone erosions, and monosodium urate crystal confirmation. Within 6 months, 59.8% and 68.6% in the colchicine twice-daily and once-daily groups, respectively, reached the serum urate target (difference −8.8%, 95% CI 1.1% to −18.7%). Colchicine prophylaxis 0.5 mg twice daily was not superior to colchicine once daily regarding flare prophylaxis after starting an XOI. As colchicine twice daily is associated with higher intolerability and costs, once-daily dosing should be preferred.