Is radiographic progression of late-onset rheumatoid arthritis different from young-onset rheumatoid arthritis? Results from the Swiss prospective observational cohort

Objective: RA can be categorized into late-onset RA (LORA, >60-65 years) and young-onset RA (YORA, 30-55 years), depending on the patient's age at disease onset. Since the average age of the population is continuously increasing, LORA will most probably gain in importance in the future. Despite this growing importance, LORA has not been the focus of much interest in the past. The aim of this study was to analyse radiographic damage progression of early disease in LORA compared with YORA patients.

Methods: We included all patients from the Swiss RA registry, Swiss Clinical Quality Management in RA, with recent-onset arthritis, either RA (disease duration ≤1 year) or undifferentiated arthritis, as diagnosed by the data-entering physician. Patients were followed for 5 years. The cut-off between YORA and LORA was operationally set at 60 years of age. The primary outcome of this study was disease progression and activity, which was assessed based on the 28-joint DAS (DAS28) and the progression of joint erosions using a validated scoring system (Ratingen score).

Results: A total of 592 patients with early disease were analysed. The age at disease onset had a Gaussian distribution, with a single peak at 54 years of age; 366 patients were categorized as YORA and 226 as LORA at disease onset. DAS28 scores were significantly higher among LORA as compared with YORA patients (4.8 vs 4.5, P = 0.049). Corticosteroids were used in 68% of LORA patients as a first-line treatment, compared with 25.4% in YORA patients (χ(2) test: 54.58; P < 0.0001). In contrast, DMARDs were used in 100% of the YORA patients as first-line treatment, compared with 91.2% of the LORA patients. During follow-up, new glucocorticoids, synthetic DMARDs or biologic DMARDs were initiated in 32.8%, 61.1% and 14.1% of all YORA patients and 17.5%, 54.6% and 6.6% of LORA patients, respectively (χ(2) test: 7.08, 22.53, 54.4; all P < 0.01). The DAS28 scores decreased in both groups during the observed time period, and the initial differences in disease activity vanished after 6 months and during the subsequent follow-up. The Ratingen score was higher in LORA than in YORA patients at inclusion (12.7 vs 5.6, P < 0.0001). The rate of radiographic progression at 5 years was similar when comparing LORA and YORA (3.3 vs 2.6, respectively, P = 0.64). The Ratingen scores at onset and during follow-up over 5 years did not clearly separate LORA and YORA into two groups, but rather, increased linearly when comparing the patients in groups per decade from 20 to 92 years of age.

Conclusion: Our results did not show LORA as a separate subgroup of RA with a different prognosis with regard to radiographic progression.