Ab0234 Clinical and Therapeutic Differences Between Late-Onset Rheumatoid Arthritis and Polymyalgia Rheumatica

Background: Elderly onset rheumatoid arthritis (EORA) is characterized by onset at age 60-65 and its prevalence has increased due to the progressive aging of the population, currently accounting for 10-33% of total rheumatoid arthritis (RA) cases. It often presents with polymyalgia symptoms at diagnosis, sometimes complicating the differential diagnosis with polymyalgia rheumatica (PMR). While patients with PMR may have synovitis as well, it is usually mild and easily controlled with corticosteroids. In EORA, treatment with disease-modifying antirheumatic drugs (DMARDs) should be like early-onset RA. However, the higher prevalence of comorbidities and polypharmacy in elderly patients, associated with clinical similarity to PMR, often leads to a tendency in real clinical practice to treat with less therapeutic intensity or less ambitious goals. Objectives: The main objective of this study is to compare the need for immunosuppressants between patients with EORA and PMR for adequate disease control. Secondary objectives include describing demographic and clinical characteristics, as well as adverse events during the follow-up of both groups. Methods: It is a retrospective longitudinal observational descriptive study. We included patients over 60 years diagnosed with PMR and EORA at HLA Moncloa University Hospital from December 2010 to December 2023. Results: Out of 141 patients, 66 were diagnosed with EORA (46.8%) and 74 (53.2%) with PMR. Both groups showed no demographic or comorbidity differences at the time of diagnosis (Table 1). Initial weakness of the shoulder and/or pelvic girdle was present in 40.9% (27) of EORA patients. Synovitis of carpal joints was observed in 41.8% (31) of PMR patients versus 89.4% (59) of EORA patients (p<0.001). Other differences in clinical presentation between PMR and EORA included small joint arthritis of the hands in 21.3% vs. 56.9% (p <0.001), knee arthritis in 13.3% vs. 30.8% (p <0.012), ankle arthritis in 6.7% vs. 24.2% (p <0.003), small joint arthritis of the feet in 0% vs. 12.1% (p <0.001), and tarsal arthritis in 1.3% vs. 7.6% (p <0.067). Elevated acute-phase reactants (APRs) were detected in 70.7% (41) of PMR patients and 64.7% (33) of EORA patients (p 0.504). Positivity for rheumatoid factor (RF) and anti-citrullinated protein antibodies (CCP) was seen in 25.8% and 34.8% of EORA patients, respectively. Regarding treatment, 93.9% of EORA patients required DMARDs compared to 34.7% of PMR patients (p<0.001). Of the EORA patients, 33.3% (22) needed more than one DMARD during follow-up versus 12% (9) of PMR patients (p 0.002). GC (corticosteroids) could be discontinued in 54.7% (35) of EORA patients and 52.1% (37) of PMR patients (p 0.765) but had to be reintroduced in 42.9% (15) and 38.5% (15) respectively (p 0.701). Global adverse events during follow-up included infections (13.3%), ischemic heart disease or arrhythmias (2.8%), gastrointestinal bleeding (3.5%), and osteoporotic fractures (14.7%; vertebral 12% and hip 0.7%). 13.3% of patients showed intolerance to prescribed medications for their rheumatic disease. 10.5% were admitted for reasons related to their rheumatological condition, and 7% exhibited dependency during follow-up. Conclusion: There is a difference in the use of DMARDs between EORA patients (96%) and PMR patients (34.7%) for disease control during follow-up. Given the absence of demographic and comorbidity differences, the correct differentiation at the onset of arthritis between PMR and EORA is significant for the proper treatment of our patients. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.