Background/Purpose: Epidemiological studies have shown that the age of onset for rheumatoid arthritis (RA) is increasing. However, associations between age of onset and joint erosion have been conflicting. Prior studies have been limited by short follow-up periods, confounding by disease activity, and lack of information about DMARDs. We investigated the effects of age of RA onset on incident joint erosion and progression of radiographic findings.

Methods: Patients diagnosed with RA within 2 years of enrollment in the Brigham and Women’s Hospital Rheumatoid Arthritis Sequential Study (BRASS), a large single-center RA registry, were included. The age of RA onset was categorized into three groups (young: ≤44 years, middle: 45-65 years, and late-onset: ≥66 years) for primary analyses and dichotomized age groups (< 60 years and ≥60 years) for sensitivity analyses. Modified total Sharp scores (mTSS) were obtained at baseline, year 2, and year 5. Incident joint erosion was defined as an erosion score greater than 0, and change in mTSS was calculated by subtracting the baseline mTSS from the mTSS at year 5. We assessed the adjusted odds ratio (OR) of incident joint erosions within a 5-year follow-up period and the adjusted change in mTSS by age category. Regression models were adjusted for rheumatoid factor (RF) / anti-cyclic citrullinated peptide (CCP) positivity, sex, and smoking status. To account for loss-to-follow-up at the year 5 X-ray, we utilized the inverse probability of censoring weighting in regression models to estimate the adjusted change in mTSS. Stratified analyses were conducted based on baseline DMARD use (DMARD use versus no DMARD use).

Results: Of the 1581 patients enrolled in BRASS between 2003 and 2023, 317 (20%) RA patients enrolled within 2 years of diagnosis with baseline X-rays. After excluding 33 patients with missing RF/CCP data, sex, or smoking status, 284 patients were eligible for analysis. Patients were categorized into three age groups (young 103 (36%), middle 135 (48%), and late 46 (16%)), and their baseline characteristics are presented in Table 1. The adjusted OR of incident joint erosion in the middle-, 4.0 (95% CI 2.2 – 7.5), and the late-onset groups, 8.2 (95% CI 3.6 – 19.2), were elevated compared with the young-onset group (Table 2). In subgroup analyses that stratified on DMARD use at baseline, adjusted ORs were similar to those among the overall population. Compatible trends were observed when the dichotomized age group was used. Compared with the young-onset group, the adjusted changes in mTSS in the middle- group, 2.8 (95% CI 0.20 – 5.4), and the late-onset groups, 1.9 (95% CI -0.26 – 4.1), were elevated (Table 3). In subgroup analyses, adjusted changes in mTSS among the DMARD use group were similar to those among the overall population. The adjusted changes in mTSS among the no DMARD use group were attenuated compared to what we observed among the overall population. Compatible trends were observed when the dichotomized age group was used.

Conclusion: The odds of incident joint erosion and change in the mTSS were increased among patients with RA onset at later ages regardless of DMARD use at baseline. These results suggest that the age of onset may define different RA phenotypes.

« Back to ACR Convergence 2024

ACR Meeting Abstracts - https://acrabstracts.org/abstract/age-of-onset-of-rheumatoid-arthritis-and-radiographic-changes/