Predictive factors of tumour necrosis inhibitor treatment persistence for rheumatoid arthritis: An observational study in 8052 patients

Objectives: To determine whether changes in ultrasonography (US) features of monosodium urate crystal deposition is associated with the number of gouty flares after stopping gout flare prophylaxis.

Methods: We performed a 1-year multicentre prospective study including patients with proven gout and US features of gout. The first phase of the study was a 6-month US follow-up after starting urate-lowering therapy (ULT) with gout flare prophylaxis. After 6 months of ULT, gout flare prophylaxis was stopped, followed by a clinical follow-up (M6 to 12) and ULT was maintained. Outcomes were the proportion of relapsing patients between M6 and M12 according to changes of US features of gout and determining a threshold decrease in tophus size according to the probability of relapse.

Results: We included 79 gouty patients (mean [±SD] age 61.8±14 years, 91% males, median disease duration 4 [IQR 1.5; 10] years). Among the 49 completers at M12, 23 (47%) experienced relapse. Decrease in tophus size≥50% at M6 was more frequent without than with relapse (54% vs. 26%, P=0.049). On ROC curve analysis, a threshold decrease of 50.8% in tophus size had the best sensitivity/specificity ratio to predict relapse. Probability of relapse was increased for patients with a decrease in tophus size <50% between M0 and M6 (OR 3.35 [95% confidence interval 0.98; 11.44]).

Conclusion: A high reduction in US tophus size is associated with low probability of relapse after stopping gout prophylaxis. US follow-up may be useful for managing ULT and gout flare prophylaxis.