Clinical features of late-onset ankylosing spondylitis: comparison with early-onset disease.

OBJECTIVE: Ankylosing spondylitis (AS) is generally observed in young patients but can occur later in life or in persons ≥ 50 years of age. Our objective was to characterize the clinical features of late-onset AS in a large multicenter national cohort.
METHODS: We studied late-onset AS in the National Registry of Spondyloarthritis of the Spanish Society of Rheumatology (REGISPONSER database) cohort (n = 1257), of whom 3.5% had onset at age ≥ 50 years versus a control group with onset at < 50 years.
RESULTS: There were no differences between late-onset and early-onset AS according to sex and family history of spondyloarthropathies. Patients in the late-onset group more often showed involvement of the cervical spine (22.7% vs 9.7%; p = 0.03) and arthritis of the upper (13.6% vs 3.0%; p = 0.002) and lower limbs (27.3% vs 15.2%; p = 0.03) as first manifestations than did patients in the early-onset group. A higher percentage of mixed forms (axial and peripheral joint disease) during the course of the disease was also recorded in the late-onset group (50% vs 24%; p = 0.0001).
CONCLUSION: Our study suggests that age at onset of AS affects the patients' presenting clinical form. Arthritis of the upper limbs requires a differential diagnosis with other conditions frequent in patients over 50 years of age, such as rheumatoid arthritis or crystal-induced arthropathy.