Age affects joint space narrowing in patients with early active rheumatoid arthritis

Background: Joint space narrowing ( JSN) in rheumatoid arthritis (RA) may be a manifestation of (primary) osteoarthritis becoming more prominent with age. We investigated the severity and predictors of JSN progression among different age groups. Methods: 10-year follow-up data of the BeSt study, a randomised controlled treat-to-target trial in early RA were used. Annual X-rays of hands and feet were scored using the Sharp/van der Heijde score (SHS). Subgroups were defined by age at baseline: 55, 40<55 and <40 years. JSN progression predictors were assessed by Poisson regression. Results: Baseline JSN scores (median (IQR)) were igher in patients 55 (2.0 (0.0-6.0)) compared with the other age groups: 1.0 (0.0-3.0) 40<55 and 0.3 (0.0-3.0) <40, p<0.001. After 10 years, total JSN and SHS were similar in all age groups. In patients 55 the mean erythrocyte sedimentation rate (ESR) over time (relative risk 1.02 (95% CI 1.00 to 1.03)