International overview on juvenile-, adult- and elderly-onset rheumatoid arthritis: The age at disease onset as a fundamental determinant of clinical presentation.

Background: Elderly-onset rheumatoid arthritis (EORA) may have peculiar findings compared to juvenile-onset RA (JORA). The aim of the work was to present and compare the clinical characteristics of RA patients with JORA and elderly-onset EORA to a group of cases with adult-onset (AORA) and to contrast the findings worldwide.

Methods: The study included 1100 adult RA patients: 209 JORA and 329 EORA, compared with 562 AORA extracted from a big data national study on 10,364 RA patients. Clinical characteristics, laboratory investigations, medications received, and co-morbidities were recorded. The disease activity index (DAS28) and health assessment questionnaire (HAQ) were estimated.

Results: The JORA cases represented 19% and EORA 29.9% of the included cohort. The mean age at onset for JORA, EORA, and AORA were 15.1 ± 2.1, 64 ± 4.2, and 36.4 ± 10 years (p < 0.0001), and the female-male ratio was 6.2:1, 2.7:1, and 7.3:1 (p < 0.0001), respectively. In EORA, body mass index (28.8 ± 5.8) and frequencies of smokers (11.6%), diabetes (12.2%), hypertension (19.8%), and osteoporosis (5.2%) were significantly higher than in JORA (26.02 ± 5; 5.3%, 2.9%, 3.8%, and 1%) and AORA (27.6 ± 5.6; 3%, 8.4%, 14.9%, and 2.3%, p = 0.016) (p < 0.0001, p = 0.001, p < 0.0001, and p = 0.009, respectively). In JORA, oral ulcers were significantly more frequent (p = 0.04); in EORA, cardiovascular manifestations (p < 0.0001) and hypothyroidism (p = 0.039) were more frequent; and DAS28 (p = 0.01) and HAQ (p = 0.038) were higher. Fibromyalgia and methotrexate administration were significantly more frequent in AORA (p < 0.0001 and p = 0.04, respectively). Rheumatoid factor, anti-cyclic citrullinated peptide, and double seropositivity were significantly more frequent in EORA (p < 0.0001, p = 0.008, and p = 0.002, respectively).

Conclusion: Comorbidities, cardiovascular manifestations, hypothyroidism, higher disease activity, and functional disability are more common in EORA patients. Key Points • Juvenile-onset and elderly-onset RA patients have notable differences compared to the adult-onset cases. • Co-morbidities and certain manifestations, including cardiovascular disease and hypothyroidism, as well as higher disease activity and functional disability, are more common in elderly-onset patients. • Fibromyalgia remains more frequent in adult-onset cases.