Risk factors associated with inadequate control of disease activity in elderly patients with rheumatoid arthritis: Results from a nationwide KOrean College of Rheumatology BIOlogics (KOBIO) registry

Objective The proportion of elderly patients with rheumatoid arthritis (RA) is continuously growing as a result of the increasing aging population. We compared disease activity between different age groups, and evaluated the clinical factors associated with high disease activity. Methods This cross-sectional study analyzed the data of RA patients enrolled in the Korean College of Rheumatology Biologics registry (KOBIO-RA) between 2012 and 2014. Disease activity between elderly (age. 65 years) and non-elderly patients (age < 65 years) was compared, and the association of clinical factors with high disease activity was assessed using a multi-variate logistic regression model. Results Of 1,227 patients in KOBIO-RA, 244 patients with RA were aged 65 years or over. In elderly patients, the proportion of men was higher (P = 0.012), and the duration of disease was longer (P < 0.001) compared with non-elderly patients. The elderly group showed a higher incidence of comorbidity (P < 0.001), and less use of methotrexate (P = 0.004). Assessment of disease activity using various composite measures showed a higher proportion of high disease activity in elderly patients than non-elderly patients. Longer disease duration, presence of comorbidity, and non-use of methotrexate were independently associated with high disease activity (P = 0.002, P < 0.001, and P = 0.029, respectively). Conclusions At enrollment of KOBIO-RA, elderly patients showed higher disease activity compared with non-elderly patients. Disease duration, use of methotrexate, and comorbidity are associated with disease activity control in Korean patients with RA.