POS1417 INTEROSSEOUS TENDON INFLAMMATION IN THE HANDS: A NOVEL FEATURE OF DEVELOPING RHEUMATOID ARTHRITIS? RESULTS FROM A LARGE MRI STUDY IN CLINICALLY SUSPECT ARTHRALGIA

Background Inflammation around the tendons of hand interosseous muscles (interosseous tendon inflammation; ITI) on MRI was recently reported in rheumatoid arthritis (RA) patients and ACPA-positive individuals with musculoskeletal symptoms. We therefore hypothesized that ITI is an early RA-feature precedes clinical arthritis. Objectives To examine this we assessed frequency clinically suspect arthralgia (CSA) compared to general population. Additionally investigated relation between other locally inflamed tissues (synovitis/tenosynovitis/osteitis) MCP-joins CSA as well association future development. Methods 667 consecutive presenting 193 symptom-free controls from population underwent contrast-enhanced hand-MRI. MRIs were evaluated for synovitis/tenosynovitis/osteitis, using scoring system (RAMRIS). followed development (median follow-up 25 months). Logistic Cox-regression used. ACPA-stratification performed. gain a better understanding anatomical relationships, 3D MRI-reconstruction lumbrical performed patient ITI. Results At presentation, 10% had ITI, 1% (p<0.001). more frequent than ACPA-negative (27% versus 7%; p<0.001). 72% also synovitis and/or tenosynovitis at MCPs (37% synovitis; 7% tenosynovitis; 27% both tenosynovitis). Also multivariable analyses, adjusted simultaneous presence likely if (OR 2.2 (95%CI 1.2-4.2)) or (9.7 (5.5-17.0)) present MCPs. The indicated continuous MCP flexor (Figure 1). developed those without (HR 4.5 (2.8-7.2)); stronger (3.9 (1.9-7.9)) (1.8 (0.9-3.4)). Conclusion arthritis, suggesting peritendinous inflammation RA-feature. Acknowledgements thank G. Kracht his assistance preparing example MR-image. Disclosure Interests None declared