Young Versus Late-Onset Rheumatoid Arthritis: A Prospective 12 Month-Follow-Up Cohort Study In An Early Arthritis Cohort

Background:Rheumatoid Arthritis (RA) is a chronic inflammatory arthropathy that can present at any age. Data regarding differences in the clinical course and outcome in Late-Onset Rheumatoid Arthritis (LORA) comparing to Young-Onset RA (YORA) are conflicting. Some studies suggested that LORA may represent a more benign form of RA (1), while others have shown a poorer prognosis in these patients (2,3). Only a few publications have included patients with early disease (3).Objectives:To compare demographic and clinical features between LORA and YORA patients, and clinical activity at baseline and after 12 months of initial therapy, in patients with early disease.Methods:We conducted a prospective cohort study of 12 months of follow-up based on an early arthritis clinic. Consecutive patients with early RA – less than 12 months duration – fulfilling ACR/EULAR 2010 and/or ACR 1987 RA classification criteria, were included and classified in LORA (disease onset ≥60 years) and YORA groups. Variables were collected from patients’ registries at first appointment after symptoms onset and after 12 months of treatment, according to a treat-to-target strategy. Independent t-test and chi-square test were performed to compare variables between groups.Results:We included 72 patients (40 (55.6%) YORA; 32 (44.4%) LORA), mean age at diagnosis 44.9±1.78 and 72.5± 1.34 years, respectively. In LORA group, the symptoms duration at first observation was shorter (17.0±2.26 vs. 23.8±2.45 weeks; p=0.046) and rheumatoid factor (RF)/ anti-citrullinated protein antibodies (ACPA) positivity was lower (28.1% vs 65.0%; p= 0.002; 31.3% vs 72.5%; p<0.001). At baseline, LORA had higher mean number of tender joints (9.76±1.29 vs 6.50±0.67; p=0.021), erythrocyte sedimentation rate (ESR) (45.7±4.98 vs. 29.3±3.74; p=0.011), C-reactive protein (CRP) (4.63±0.91 vs 2.22±0.46; p=0.022) and disease activity using DAS28-3V (5.11±0.28 vs 4.42±0.19; p=0.046), CDAI (33.7±3.39 vs 23.6±2.18; p=0.015) and SDAI (37.4±3.43 vs 26.3±2.57; p=0.015). At the end of follow-up, there were no statistically significant differences between LORA and YORA groups regarding treatment, disease activity and patient-reported outcomes at 12 months (Table 1).Table 1.Clinical variables assessment at 12 months of follow-up.EORAYORAp-valueTreatment, % users Corticosteroids93.397.4p= 0.576 Methotrexate76.774.4p=0.825 Hydroxychloroquine43.346.2p= 0.815 Sulfasalazine10.015.4p=0.722 Leflunomide3.305.10p=1.000 TNF blockers3.305.10p=0.717DAS28-3V, mean (SD)1.99±0.152.22±0.15p=0.286SDAI, mean (SD)4.64±1.357.68±1.39p=0.128CDAI, mean (SD)4.15±1.176.56±1.32p=0.180Swollen joints, mean (SD)1.29±0.491.03±0.25p=0.613Tender joints, mean (SD)0.32±0.131.28±0.53p=0.084ESR, mean (SD)10.6±1.799.43±1.14p=0.585CRP, mean (SD)0.44±0.090.50±0.15p=0.730PtGA, mean (SD)21.8±5.9029.2±6.11p=0.387PhGA, mean (SD)10.6±3.2613.1±3.11p= 0.593Pain intensity (VAS), mean (SD)20.7±5.8232.7±6.30p=0.169HAQ, mean (SD)0.23±0.0890.54±0.13p=0.060Legend: DMARD- disease-modifying anti-rheumatic drug; TNF- tumoral necrosis factor; SDAI-simplified disease activity score; CDAI- clinical disease activity score; PtGA/ PhGA – patient’s/ physician’s global assessment of general health; VAS- visual analogic scale; HAQ- health assessment questionnaire.Conclusion:LORA patients presented with higher disease activity manifested by higher joint counts and laboratory inflammatory markers but lower RF and ACPA positivity proportion. Despite the more aggressive clinical presentation, the clinical and functional outcomes at 12 months were similar between LORA and YORA patients.References:[1]Deal et al. Arthritis Rheum 1985;28(9):987-94.[2]Arnold et al. Rheumatology (Oxford) 2014; 53:10751086.[3]Romão et al. Semin Arthritis Rheum 2020;0(4):735-743.Disclosure of Interests:None declared