Patients and Methods : We performed a 6-month multicentre prospective study including patients with 1) proven gout, 2) presence of US features of gout (tophus and/or double contour [DC] sign) at the knee and/or first metatarsophalangeal joints, and 3) no current ULT. US evaluations were performed at baseline and at months 3 and 6 (M3, M6) after starting ULT. Outcomes were 1) the change in US features of gout at M6 according to final (M6) serum uric acid (SUA) level (high, > 360 µmol/l; low, 300–360 µmol/l; very low, < 300 µmol/l), and 2) correlation between changed US features and final SUA level.
Results : We included 79 gouty patients (mean ± SD, age 61.8 ±14 years, 91% males, disease duration 6.3 ± 6.1 years). Baseline SUA level was 530 ± 97 µmol/l. At least one US tophus and DC 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 SUA level, respectively. We found a significant decrease in US features of gout among patients with the lowest SUA level (p <0.001). Final M6 SUA level was positively correlated with decreased size of tophus (r=0.54 [95% confidence interval: 0.34; 0.70], p <0.0001), and inversely correlated with proportion of DC sign disappearance (r=-0.59 [-0.74; -0.40]).
Conclusions : US can show decreased urate deposition after ULT, which is correlated with decreased SUA level. The responsiveness of US in gout is demonstrated and can be useful for gout follow-up and adherence to ULT.