THU0130 Exploring the minimum paired joint set of ultrasonography to predict clinically significant residual synovitis in rheumatoid arthritis patients with remission

Background Patients with rheumatoid arthritis (RA) who achieved clinical remission sometimes have synovitis detected by joint ultrasonography (US) (1). This residual synovitis has been shown to be predictive of insidious radiographic progression, flares after tapering or cessation of DMARDs. Since it is difficult to examine all joints by US in daily clinical practice, several joint combinations have been proposed for optimal and/or feasible assessments of joint inflammation in patients with RA. Objectives To find the minimum number of paired joint set for US to predict clinically significant residual synovitis. Methods A comprehensive US assessment of joints was performed in 109 RA patients who achieved DAS28-CRP remission or low disease activity. Totally 40 (20 pairs) of joints including metacarpophalangeal (MCP) 1 to 5, proximal interphalangeal (PIP) 1 to 5, wrist, elbow, shoulder, knee, ankle, metatarsophalangeal (MTP) 1 to 5 joints were evaluated according to the EULAR recommendation (2). Residual synovitis was defined as synovial hypertrophy with grey scale (GS) score greater than 1 or GS score 1 with any power Doppler (PD) signal, using semi quantitative scoring system (scale 0 to 3). Results 73 of 109 patients (67%) had at least one residual synovitis, and 39 of 73 patients (53.4%) had residual synovitis at least two different joints. As shown in table 1, residual synovitis at wrist and knee joints were found in 54.8% and 53.4% of 73 patients respectively, while for residual synovitis of another joints were less than 20% of patients. Solitary residual synovitis was most frequent in wrist and knee joints. By adding and combining joints which frequently found to have residual synovitis, we found that combination of wrist, knee, ankle, elbow, MCP1, and MCP2 joints (6 pairs) could detect residual synovitis in 94.5% of patients (table 2). Using the fact that one patients can have more than one residual synovitis at different joints and the tendency of residual synovitis to be found at some particular joints, we might find minimum pairs set of joint ultrasonography to detect residual ultrasound-defined synovitis. This could minimise the efforts needed to perform thorough joint US, while keeping the sensitivity high enough to detect any residual synovitis. Conclusions Patients achieved DAS28-CRP remission often had residual synovitis. The residual synovitis had tendency to be distributed at wrist, knee, ankle, elbow, MCP1, and MCP2, joints frequently used in activities of daily life. We propose this combination of joints as the minimum paired joint set to predict ultrasonographic remission. References [1] Foltz V, et al. Arthritis & Rheumatology2012;64:67–76. [2] Backhaus M, et al. Ann Rheum Dis2001;60:641–649. Disclosure of Interest None declared