OP0152 Is sonographic phenotype of late-onset rheumatoid arthritis different from young-onset rheumatoid arthritis? results from the birmingham early arthritis cohort

Background The incidence of rheumatoid arthritis (RA) is generally seen as a bimodal age distribution, which consists of young-onset RA (YORA) and late-onset RA (LORA). Although a retrospective study has reported some differences in sonographic changes between LORA and YORA, little is known whether there are any differences in the clinical and sonographic phenotypes between these two groups during the early disease phases. Objectives To compare the clinical and sonographic characteristics between YORA and LORA during the early phases of disease. Methods DMARD–naive patients with clinically apparent synovitis of at least one joint and symptom duration of three months or less were included in the analysis. Patients underwent clinical, ultrasonography and radiological assessments at baseline and final outcomes were determined at 18 months; patients were classified as having RA (according to either the 1987 ACR and/or 2010 ACR/EULAR criteria), a non-RA persistent arthritis or a resolving arthritis. Sonographic assessment included MCP, PIP, wrist, MTP, knee, ankle, elbow joints and wrist, hand flexor, bicep tendon, anteromedial-lateral tendon compartments. The presence and absence of joint synovitis and tenosynovitis were recorded according to the EULAR/OMERACT consensus definition. Results 150 patients were included in the analysis. At 18 months, 37 patients developed YORA, 36 developed LORA, 27 developed non-RA inflammatory arthritis and 50 patients had resolving arthritis. The clinical characteristics between YORA and LORA were not significantly different at initial presentation (table 1). The ultrasound characteristics differed between these two groups. LORA patients were more likely to have shoulder biceps tendon tenosynovitis (GS; p=0.026, PD; 0.037), elbow joint synovitis (GS; p=0.010, PD; p=0.037), MCP1 (PD; p=0.032) and MCP5 (GS; p=0.035) synovitis, compared to YORA patient. YORA patients were more likely to have MTP synovitis (GS; p=0.013) compared to LORA patients. Conclusions This is the first study to describe the difference of both clinical and sonographic inflammation of YORA and LORA in recent-onset DMARD-naive RA patients in a longitudinal study. There are differences in US-detected joint and tendon inflammation despite similarities in clinical characteristics. The prognostic value of the differences in US pathology between these two groups should be further explored. Disclosure of Interest None declared