Should we reconsider the definition of elderly-onset rheumatoid arthritis in an ageing society?

Objectives The management of elderly-onset rheumatoid arthritis (EORA) is challenging due to progressive functional disability, increased comorbidities, and high drug-related risks. EORA is defined as disease onset after 60 years since 1985. We assessed whether this cut-off age was optimal in a progressively ageing society. Methods This study used two cohorts of consecutive rheumatoid arthritis (RA) patients: the Nippon Medical School (NMS) cohort (n = 204) and the Keio cohort (n = 296). Clinical findings independently correlated with the age of RA onset were selected as 'EORA features' from previously reported EORA characteristics using univariable and multivariable regression analyses. Receiver operating characteristic curve analysis was conducted to determine the cut-off age that best selected patients with all EORA features. Results Acute onset, negative anti-cyclic citrullinated peptide antibody, and high erythrocyte sedimentation rate were selected as 'EORA features' in both cohorts. Patients with all EORA features were more numerous with age and almost exclusively older than 65 years. The optimal EORA cut-off age was 73 years with an area under the curve (AUC) of 0.82 in the NMS cohort and 68 with an AUC of 0.93 in the Keio cohort. In the NMS cohort, Health Assessment Questionnaire-Disability Index and comorbidities in patients with disease onset between 60 years and the projected cut-off age were similar to those in younger-onset RA, but differed from those in patients with disease onset older than the projected cut-off age. Conclusion The optimal EORA cut-off age was greater than the conventional definition, but this needs to be validated in different patient populations.