SAT0011 What is Undifferentiated Arthritis (UA) in 2013, and can Progression to Rheumatoid Arthritis (RA) be Predicted?

Background In applying 2010 criteria to patients with early inflammatory arthritis, the weighting of serology in the criteria is such that the majority of ACPA positive arthritis patients are classified as RA. A significant proportion of patients with UA have persistent disease1,2. Differences between ACPA negative(-) and ACPA positive(+) patients suggest their disease pathogenesis is divergent. Objectives Compare UA and ACPA- RA, and determine clinical and/or ultrasound (US) features predictive of progression to RA. Methods DMARD-naïve patients with UA or RA (2010 criteria) with outcomes available at 6 months were selected from the Leeds Early inflammatory arthritis cohort (recruitment since 2010). Steroid within the preceding 4 weeks was an exclusion. Patients with UA were categorised as palindromic, oligo- or polyarthritis according to intermittent or persistent joint tenderness and/or swelling and involvement of