Background and objectives Elderly-onset rheumatoid arthritis (EORA), starting after the age of 60, is a subset of disease with different characteristics from the classic younger-onset RA (YORA). We aimed to compare clinical and pathological features between these two disease subsets in the Barts Early Arthritis Cohort (BEAC).
Material and methods We included BEAC patients fulfilling ACR 2010 criteria and assessed clinical and pathological variables at baseline and at 6 months of DMARD therapy. The primary outcome was the achievement of low disease activity (LDA) according to DAS28 at 6 months. We used multivariate logistic regression to determine predictors of LDA at 6 months.
Results We included 140 patients, 99 YORA and 41 EORA. EORA patients were more frequently male (51.2 vs. 26.3, p = 0.004) and Caucasian (68.3 vs. 39.4, p = 0.02), had more proximal joint involvement at presentation (55.0 vs. 35.1, p = 0.031), more common abrupt (27.5 vs. 4.1, p < 0.001) and polymyalgia rheumatica (PMR)-like onset (23.7 vs. 0, p < 0.001), weight loss (15.0 vs. 4.1, p = 0.026), anaemia (48.6 vs. 28.4, p = 0.033), extra-articular manifestations (27.5 vs. 6.2, p = 0.004) and cardiovascular comorbidity (73.2 vs. 29.3, p < 0.001). At baseline, disease activity parameters, including ESR, CRP, joint counts, and composite scores (DAS28, CDAI and SDAI), were similar between both groups. Synovial pathotype classification (ectopic lymphoid-like structures positive (ELS+); diffuse myeloid infiltrate or non-inflammatory/pauci-immune) did not reveal differences between groups as a whole (p = 0.12). However, EORA patients presented pauci-immune pathotype less frequently (25.0 vs. 44.3, p = 0.045). Macrophage, B-cell, T-cell and plasmocyte semi-quantitative scores were also similar. At 6 months (n = 105), EORA (OR = 0.28, p = 0.047), female gender (OR = 0.23, p = 0.016), current smoking (OR = 0.11, p = 0.002) and high baseline DAS28 (OR = 0.41, p < 0.001) were negatively associated with reaching DAS28 LDA. Contrastingly, PMR-like onset was strongly predictive of DAS28 LDA (OR = 63.9, p = 0.004).
Conclusions In an early arthritis cohort, EORA patients presented different clinical features at presentation, but similar synovial pathological characteristics. Adjusting for other significant factors such as gender, smoking, baseline DAS28 and PMR-like onset, EORA was negatively associated with the achievement of LDA at 6 months according to DAS28.