Ultrasound evaluation in follow-up of urate-lowering therapy in gout: the USEFUL study.

OBJECTIVES: We aimed to determine the ability of ultrasonography (US) to show disappearance of urate deposits in gouty patients requiring urate-lowering therapy (ULT). METHODS: We performed a 6-month multicentre prospective study including patients with: proven gout; presence of US features of gout (tophus and/or double contour sign) at the knee and/or first metatarsophalangeal joints; and no current ULT. US evaluations were performed at baseline and at months 3 and 6 (M3, M6) after starting ULT. Outcomes were: the change in US features of gout at M6 according to final (M6) serum urate (SU) level (high, > 360 µmol/l, i.e. > 6 mg/dl; low, 300-360 µmol/l, i.e. 5-6 mg/dl; very low, < 300 µmol/l, i.e. < 5 mg/dl); and correlation between changed US features and final SU level. RESULTS: We included 79 gouty patients (mean ± s.d., age 61.8 (14) years, 91% males, disease duration 6.3 (6.1) years). Baseline SU level was 530 ± 97 µmol/l (i.e. 8.9 mg/dl ± 1.6mg/dl). At least one US tophus and double contour sign was observed in 74 (94%) and 68 (86%) patients, respectively. Among the 67 completers at M6, 18 and 39 achieved a very low and low SU level, respectively. We found a significant decrease in US features of gout among patients with the lowest SU level (P < 0.001). Final M6 SU level was positively correlated with decreased size of tophus (r = 0.54 [95% CI: 0.34, 0.70], P < 0.0001), and inversely correlated with proportion of double contour sign disappearance (r=-0.59 [-0.74, -0.40]). CONCLUSION: US can show decreased urate deposition after ULT, which is correlated with decreased SU level. The responsiveness of US in gout is demonstrated and can be useful for gout follow-up and adherence to ULT.

UltraSound evaluation in follow-up of urate-lowering therapy in gout phase 2 (USEFUL-2): Duration of flare prophylaxis.

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 [AUC 0.649 (95% confidence interval 0.488; 0.809)]. 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 lower probability of relapse after stopping gout prophylaxis. US follow-up may be useful for managing ULT and gout flare prophylaxis.

An optimal ultrasonographic diagnostic test for early gout: A prospective controlled study.

Objective To identify the optimal sites for classification of early gout by ultrasonography. Methods Sixty patients with monosodium urate crystal-proven gout (25 with early gout [≤2-year symptom duration], 35 with late gout [>2-year symptom duration], and 36 normouricemic healthy controls) from one centre were prospectively evaluated. Standardized blinded ultrasound examination of 36 joints and the triceps and patellar tendons was performed to identify tophi and the double contour (DC) sign. Results Ultrasonographic sensitivity was lower in early than late gout. Binary logistic regression analysis showed that two ultrasonographic signs (tophi in the first metatarsophalangeal joint [odds ratio, 16.46] and the DC sign in the ankle [odds ratio, 25.18]) significantly contributed to the final model for early gout diagnosis (sensitivity and specificity of 84% and 81%, respectively). The inter-reader reliability kappa value for the DC sign and tophi was 0.712. Conclusions Four-joint investigation (both first metatarsophalangeal joints for tophi and both ankles for the DC sign) is feasible and reliable and could be proposed as a screening test for early ultrasonographic gout classification in daily practice.