AB0066 MRI-Detected Osteitis Is Not Associated with The Presence or Level of ACPA Alone, but with The Combined Presence of ACPA and RF

BackgroundIn patients with rheumatoid arthritis (RA) bone marrow edema (BME) as observed by magnetic resonance imaging (MRI) represents osteitis with infiltration of leucocytes and an increased number of osteoclasts. Both BME and anti-citrullinated protein antibodies (ACPAs) are predictors of radiographic progression in RA and recent data indicate that ACPA can directly activate osteoclasts. These findings together lead to the hypothesis that ACPA is associated with BME; indeed, two small studies observed an association between BME and ACPA. Thus far the association of ACPA with other forms of MRI-detected inflammation (synovitis and tenosynovitis) has not been thoroughly explored. Furthermore, it is unknown if the association with MRI-detected inflammation is only present for ACPA or also for other RA-related auto-antibodies.ObjectivesThis study aimed to investigate the associations of ACPA, RF and antiCarP with BME, synovitis and tenosynovitis.MethodsA total of 589 early arthritis patients, included in the Leiden Early Arthritis Clinic cohort, underwent contrast-enhanced 1.5T MRI of the unilateral wrist, metacarpophalangeal and metatarsophalangeal joints at baseline. BME, synovitis and tenosynovitis were scored according to the RAMRIS-method. ACPA, rheumatoid factor (RF) and anti-carbamylated protein (antiCarP) antibodies were determined at baseline.ResultsBME, synovitis and tenosynovitis were concomitantly present on MRI. In univariable analyses, ACPA-positive patients had higher BME-scores than ACPA-negative patients (median scores 4.5 vs. 2.0, p