Higher risk of poor functional outcome and unfavorable clinical events for late-onset rheumatoid arthritis: results from the IORRA cohort.

Objectives: To compare treatment outcomes in patients with late-onset rheumatoid arthritis (LORA) and younger-onset rheumatoid arthritis (YORA).
Methods: We analyzed patients diagnosed with early rheumatoid arthritis (disease duration < 2 years) between 2000 and 2016 in the IORRA cohort. Patients were categorized into LORA (onset at ≥ 65 years) and YORA (onset at < 65 years). The primary outcomes were changes in Clinical Disease Activity Index (CDAI) and Japanese version of the Health Assessment Questionnaire (J-HAQ) at Year 5. The secondary outcomes included the incidence of prespecified adverse events.
Results: Methotrexate, biological disease-modifying anti-rheumatic drugs, and glucocorticoids were used in 70.6%, 8.4%, and 38.0% of the LORA group (n = 813, median age: 71 years), and 81.6%, 19.4%, and 32.0% of the YORA group (n = 2,457, median age: 51 years). Both groups exhibited significant initial improvements in CDAI and J-HAQ scores. At Year 5, mean CDAI scores were 4.39 and 4.03 for the LORA and YORA groups, respectively. J-HAQ score for YORA remained stable below 0.5 after Year 2, whereas that for LORA worsened progressively. At Year 5, mean J-HAQ scores were 0.56 for LORA and 0.33 for YORA. Patients with LORA had a higher incidence of adverse events, with adjusted hazard ratios of 4.70 for death and 2.58 for malignancy.
Conclusions: Patients with LORA and YORA exhibited similar improvements in disease activity over 5 years; however, those with LORA demonstrated a more pronounced decline in physical function.
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