Correlation of Ultrasound Synovitis Joint Count with Disease Activity and Its Longitudinal Variation with Treatment Response to Etanercept in Rheumatoid Arthritis.

More research is needed into rheumatoid arthritis (RA), and ultrasound (US) synovitis is a promising factor for assisting in the management of RA; however, related research is extremely limited. The goal of this study was to evaluate the correlation of US synovitis joint count with clinical features, and its longitudinal changes with treatment response to etanercept in RA. We consecutively enrolled 117 people with active RA being treated with etanercept. US synovitis joint count was evaluated in 28 joints at baseline (W0), week 4 (W4), week 12 (W12) and week 24 (W24) after initiation of etanercept treatment. The mean (±standard deviation), median, inter-quartile range, and total range of the US synovitis joint count at W0 were 9.3 ± 4.0, 9.0, 7.0-11.0 and 2.0-21.0, respectively. US synovitis joint count was positively associated with tenderness joint count, swollen joint count, erythrocyte sedimentation rate, 28-joint Disease Activity Score based on erythrocyte sedimentation rate and Health Assessment Questionnaire-Disability Index score. Then participants were categorized into response and non-response groups according to their response status at W24. Further analyses showed that US synovitis joint count gradually decreased from W0 to W24, and displayed a more notable declining trend in the response group compared with the non-response group. In addition, US synovitis joint count at W0 and W4 was similar between groups, but at W12 and W24 it was markedly decreased in the response group compared with the non-response group. In conclusion, US synovitis joint count correlates with disease activity, and its longitudinal decrease is associated with treatment response to etanercept in RA.