Regional Trends and Patterns of Axial Spondyloarthritis in Latin America: A Study From the ESPALDA Registry...

To compare demographic, clinical, functional, and therapeutic characteristics of patients with axial spondyloarthritis (axSpA) across 3 Latin American regions using data from the Registro de Espondiloartritis Axial de America (ESPALDA) registry between January 2019 and December 2024.

This cross-sectional study included 418 patients diagnosed with axSpA who fulfilled the Assessment of SpondyloArthritis international Society classification criteria. Participants were recruited from 3 Latin American regions: northern (Mexico), Andean (Colombia, Ecuador, Peru, Venezuela), and southern (Argentina, Chile, Paraguay, Uruguay). Collected data included demographic characteristics, HLA-B27 status, extraarticular manifestations, disease activity, radiographic damage, and treatments.

The northern region showed the highest prevalence of HLA-B27 (81%) and uveitis (36.3%), along with lower frequencies of peripheral involvement and fewer patients with magnetic resonance imaging-defined sacroiliitis (7.3%; all P ≤ 0.003). In contrast, the southern region reported a later onset of inflammatory back pain (median 39 vs 22 years; P = 0.01), higher Bath Ankylosing Spondylitis Functional Index scores (median 4.6 vs 3.3, P = 0.005), and a lower response to nonsteroidal antiinflammatory drugs (59.8% vs 79%; P = 0.001). Use of biologic disease-modifying antirheumatic drugs was lowest in the northern region (34.7%) compared with the Andean (57.9%) and southern (53.8%) regions (P ≤ 0.002 for northern vs other regions). The median diagnostic delay was 40.9 (IQR 12.0-121.1) months, with no significant regional differences.

Two clinical phenotypes of axSpA appear to exist in Latin America: a predominantly axial, HLA-B27-positive phenotype in the northern region, and a second phenotype in the Andean and southern regions characterized by greater peripheral involvement and, in the southern region, later symptom onset and worse functional status.