High-resolution ultrasound evaluation in the follow-up of treat to target urate-lowering therapy in gout: an observational study

Abstract Background: The monitoring of treat-to-target (T2T) urate-lowering therapy (ULT) for gout is crucial for the assessing treatment response. However, evidence is lacking about clinical remission on ultrasound (US). The aim of this study was to observe the changes in three outcome domains (urate deposition, joint inflammation and bone erosion) in patients with ULT within 1 year, evaluate the effect of target treatment and analyse the relationships between clinical factors and US features. Methods: The elementary lesions of the bilateral knee, ankle and first metatarsophalangeal joints were evaluated by US before and after 3,6 and 12months of treatment. Urate deposition was assessed by the maximum long and short axis diameters of the tophi and dichotomous data of the double-contour (DC) sign and aggregates. After each follow-up, the most obvious lesions were selected for repeated observation. The effective clearance rates of these three signs in different time groups were compared. A Global OMERACT–EULAR Synovitis Score (GLOESS) was calculated for these three paired joints to observe the remission and recurrence of inflammation. Bone destruction was scored at each time point. The correlation between serum uric acid (sUA) levels and tophi size changes was analysed. Results: This cohort contained 79 patients. The long and short axis diameters of tophi showed a different descending tendency. The decrease of sUA levels correlated with the decrease of long axis values, but not with the short. For tophi, there was no significant difference in the clearance rate between different time groups, while for DC sign and aggregates, significant differences were found by paired comparison. The GLOESS was significantly lower after 6 months of therapy. Bone erosion had not been improved after 1 year of ULT.Conclusion: The decrease in sUA levels was not completely parallel to the decrease in tophi size. ULT with different intensities should be formulated according to different crystal deposition conditions under US assessment. Subclinical inflammation was gradually controlled after 6 months of therapy and can be sensitively observed by US. Joint damage was relatively stable within 12 months of ULT.