Evidence That Both the Disease Course & Structural Outcomes in RA Have Become Less Severe over Time. A 25-Year Longitudinal Data Analysis Based on Two Consecutive UK Inception Cohorts

Background Evidence suggests that disease expression and course in RA has become less severe. It is unclear whether this is due to changes in disease phenotype/expression or reflects earlier more effective therapy. Objectives To test the hypothesis that the course of RA & structural outcomes have become less severe in recent years. Methods A total of 2701 DMARD-naïve patients were recruited over 25yrs in two UK RA inception cohorts with a single continuous mode of data collection:Early RA Study (9 centres, 1986-1998) & Early RA Network (23 centres, 2002-2012). Standardized clin/lab & x-ray measures were performed at baseline prior to DMARDs & yearly, along with comorbidities & in-patient hospital episodes including orthopaedic surgery (OS). Clinical databases were supplemented & validated with UK sources: National Joint Registry, Hospital Episode Statistics & National Death Register. Therapies included DMARDs, steroids & biologics based on standard UK practices and published guidelines. Results Of 2701 early RA patients, 67% were female, mean age 56yrs (±14) & 62% rheumatoid factor positive (RF+ve), median follow-up 9 yrs (IQR 13). Over 25yrs of study, a shift towards more intensive therapy was seen: from monotherapy (1st choice DMARD: sulphasalazine in the 1st decade, methotrexate in the 2nd) to dual combinations, triple therapy & biologics. Graphics will dispay these trends. Over the recruitment periods, there was no significant change in gender (p=0.648), RF+ve (p=0.775), or erosions at baseline (p=0.695). Age at disease onset increased by 0.22 years/year (p=0.001), indicating a later disease-onset over time despite times from symptom onset to specialist diagnosis changing little (median 6 months). In models controlling for centre, age & gender, baseline clin/lab variables that significantly decreased with every year included:DAS (by 0.03 unit,p