Background/Purpose: The population of elderly individuals with rheumatoid arthritis (RA) is increasing. The aim of this study was to assess whether age at disease onset affects disease activity and functional outcome in patients with RA.  We hypothesized that patients with elderly-onset RA (EORA) would have more severe disease and higher disability compared to younger-onset RA (YORA) patients.

Methods: All patients enrolled in the Ontario Best Practices Research Initiative (OBRI), a clinical registry of early and established RA patients followed in routine care, were included in the study (N= 1981). Patients were categorized as EORA if their disease onset was ³ 60 years of age (N=1516) and as YORA if disease onset occurred before 60 years (N=465). Outcomes assessed were disease activity (measured by Disease Activity Score 28 [DAS28]) and function (assessed by Health Assessment Questionnaire [HAQ]) at entry into the registry.  Differences between two groups were compared using chi-square test and t-test. Separate linear regression models, adjusted for gender and disease duration were performed, with p <0.05 considered statistically significant.

Results: The mean (SD) age of patients was 57.4 (12.9) years. The mean (SD) disease duration in the group was 8.5 (9.4) years. EORA patients were less likely to be rheumatoid factor and anti-citrullinated protein antibody positive (p<0.05).  At entry into the registry, EORA patients were more likely to be on disease-modifying agents (79.4% vs. 66.1%, p<0.001) and steroids (27.4% vs. 22.9%, p=0.05), and less likely to be taking biologic therapy (12.1% vs. 25.7%, p<0.001) compared to YORA patients.  Mean DAS28 scores were significantly higher among EORA patients compared to those with YORA (4.6 vs. 4.3, p=0.002).  In a stratified analysis, this association was seen for those with early disease (< 2 years) but not for longer disease duration (Table 1). There was a non-significant trend towards higher HAQ scores among EORA patients compared to YORA patients. In a regression analysis with disease duration as a continuous variable, there was a significant association between EORA and higher disease activity and greater disability (p<0.05).

Table 1: Mean DAS28 and HAQ scores at entry into OBRI, stratified by age at disease onset and disease duration

Conclusion: Research in the area of EORA has produced mixed results in terms of disease activity and functional disability. Our study demonstrates that older age at disease onset is associated with greater disease activity and functional disability at entry into OBRI. Disease duration appears to influence these outcomes. Further study is required to evaluate which components of the DAS28 may differ among EORA vs. YORA and what drives these potential differences. Furthermore, evaluating the role of factors including comorbidities is necessary to understand the reasons for higher disease activity and poor functional outcome among patients with EORA.