Abstract

Background: In patients with gout receiving uric acid-lowering therapy, musculoskeletal ultrasound has the potential to observe changes in gout lesions.
Aims: To analyze the effectiveness of uric acid-lowering therapy in patients with gout over one year using musculoskeletal ultrasound as a monitoring technique.
Study Design: Prospective cohort study.
Methods: A total of 215 patients meeting the 1977 American College of Rheumatology gout classification criteria and treated with uric acid-lowering therapy were separated into two groups, treat-to-target and treat-to-non-target depending on the target serum urate levels. Lower extremity joints were evaluated by ultrasound before therapy (M₀), as well as three (M₃), six (M₆), and twelve (M₁₂) months after therapy. At various moments during uric acid-lowering therapy, the tophus size and the semiquantitative ultrasound scoring system of double contour sign were measured in the treat-to-target and treat-to-non-target groups.
Results: Ninety-five tophi (45 in treat-to-target and 50 in treat-to-non-target) and sixty-seven double contour sign (34 in treat-to-target and 33 in treat-to-non-target) were evaluated longitudinally. In both groups, the long diameter, short diameter, and area of tophus in treat-to-target decreased as the duration of uric acid-lowering treatment increased. Differences in the long diameter of tophus between M₁₂ and M₀, M₃ and M₆ were statistically significant (P < 0.05), while differences between the other time points were not significant (P > 0.05). No statistically significant differences were observed in the short diameter and the area of tophus between M₀ and M₃ (P > 0.05), while there were statistically significant differences between other periods (P < 0.05). In treat-to-non-target, the long diameter, short diameter, and area of tophus showed a slight increase at different uric acid-lowering therapy time points. The differences in the long diameter, short diameter, and area of tophus at different uric acid-lowering therapy time points were not significant (P > 0.05). The semiquantitative ultrasound scoring system of double contour sign of treat-to-target and treat-to-non-target showed a decreasing trend with increasing uric acid-lowering therapy time, with a more pronounced drop in treat-to-target than treat-to-non-target. In treat-to-target, the difference in the semiquantitative ultrasound scoring system of double contour sign at each uric acid-lowering therapy time point was significant (P < 0.05). In treat-to-non-target, the difference in semiquantitative ultrasound scoring system of double contour sign scores between M⁰ and M³ was not statistically significant (P >0.05), but it was statistically significant for the remaining time points (P < 0.05).
Conclusion: After one year of uric acid-lowering therapy in patients with gout, an ultrasound indicated that the size of tophus and the semiquantitative ultrasound scoring system of double contour sign score decreased dramatically in the treat-to-target group. Semiquantitative ultrasound scoring system of double contour sign score was dramatically reduced in the treat-to-non-target group, but the size of the tophus remained the same. Therefore, musculoskeletal ultrasound is an effective tool to monitor the efficacy of uric acid-lowering therapy.