Features and Outcomes of Elderly Rheumatoid Arthritis: Does the Age of Onset Matter? A Comparative Study From a Single Center in China

Introduction The aim of this work is to investigate the clinical and radiological characteristics of elderly rheumatoid arthritis and compare the outcomes between the two subgroups, elderly- and young-onset rheumatoid arthritis (EORA and YORA, respectively). Methods We conducted a retrospective case-control study on the elderly rheumatoid arthritis patients in our medical center. EORA was defined as the patient whose onset age was above 60. Results A total of 142 elderly rheumatoid arthritis patients were admitted, with 79 patients in EORA and 63 in YORA group. Inflammatory parameters including C-reactive protein, D-dimer, serum ferritin, and platelet count levels were all higher in the EORA group than those in YORA. EORA patients showed a higher score of health assessment questionnaire's disability index ( p = 0.01) and patient global health assessment ( p = 0.049), but a lower status of modified total sharp score ( p = 0.001). Bivariate logistic regression analysis revealed that elderly onset of the disease (OR 2.30, 95% CI [1.45–3.77]), age (OR 2.04, 95% CI [1.22–3.41]), high disease activity (OR 1.90, 95% CI [1.17–3.32]), and red blood cell distribution width (OR 1.81, 95% CI [1.03–3.19]) were independent prognostic factors of disability. Age (OR 0.25, 95% CI [0.07–0.91]), disease duration (OR 2.73, 95% CI [0.97–7.70]), and co-morbid diabetes mellitus (OR 118.10, 95% CI [3. 50–3985.57]) independently contributed to radiographic joint damage in the elderly population. EORA patients showed increased death incidents and worse prognosis than YORA. Cox regression analysis reveals that comorbid hypertension (HR 12.02, 95% CI [1.08–133.54]), interstitial lung disease (ILD) (HR 85.04, 95% CI [4.11–1759.19]), and compressive fracture (HR 85.04, 95% CI [4.11–1759.19]) are independent predictors of mortality, and that ILD (HR 50.21, 95% CI [5.56–335.33]) and pulmonary hypertension (HR 25.37, 95% CI [3.03–265.81]) are independent predictors of no disease remission in the EORA patients. Conclusions The distinct features of EORA patients make EORA a unique entity different from “classic rheumatoid arthritis”. EORA patients develop an upgraded systemic inflammatory status, more declined life quality, and worse prognosis than the elderly YORA. Better control of the comorbidities like ILD and diabetes mellitus may benefit the management of elderly rheumatoid arthritis. Further investigation regarding the pathogenesis and therapeutic strategies of EORA is urgently warranted.