Regional Differences Found in Phenotypes of Patients With axSpA

The clinical phenotype of axial spondyloarthritis (axSpA) widely differs throughout the world, according to study of patients from 27 countries published in the journal Rheumatology.

“Knowledge of the phenotypic characteristics of patients in different regions is vital for early diagnosis, early initiation of disease treatment, and improved management of axSpA patients,” wrote corresponding author Marco Garrido-Cumbrera, PhD, of the University of Seville, Seville, Spain, and study coauthors. “Therefore, this information may be useful for rheumatologists to reduce the disease burden of their patients.”

The International Map of Axial Spondyloarthritis (IMAS) online survey, which took place between 2017 and 2022, included 5557 patients with axSpA. Among them, 3493 were from Europe, 770 were from North America, 600 were from Asia, 548 were from Latin America, and 146 were from South Africa. Researchers were interested in differences in clinical phenotype presentation throughout the 5 geographic regions.

In Latin America, the age at symptom onset was higher than the average of 25 to 30 years observed elsewhere, according to the study. South Africa had the longest diagnostic delay at roughly 11 years; Asia had the shortest at 4.2 years. In all regions, the HLA-B27 test was positive in less than 80% of patients. Asia had the highest rate of HLA-B27 positivity (78.2%), and Latin America had the lowest (65.1%). Europe had the lowest rate of extra-musculoskeletal manifestations.

“North America has the highest prevalence of uveitis and psoriasis, while the highest proportion of patients with IBD [inflammatory bowel disease] and physical comorbidities was found in South Africa,” researchers wrote.

The overall average score on the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was 5.4: South Africa had the highest BASDAI average at 6.0, and Asia had the lowest at 4.9, the study found.

Most patients had taken nonsteroidal anti-inflammatory drugs (NSAIDs) to manage their condition. Less than half had ever taken conventional synthetic disease-modifying antirheumatic drugs (DMARDs), and nearly half had ever taken biologic DMARDs. Biologic DMARDs were used more frequently in the Americas, and conventional synthetic DMARDs and NSAIDs were used more frequently in Latin America and South Africa.

“This heterogeneity in the use of different drugs to treat axSpA in the different IMAS regions could be due to limitations in access to these drugs in the countries or the lack of effectiveness of these drugs, leading to the use of other drugs,” researchers wrote.

Reference

Poddubnyy D, Sommerfleck F, Navarro-Compán V, et al. Regional differences in clinical phenotype of axial spondyloarthritis: results from the International Map of Axial Spondyloarthritis (IMAS). Rheumatology. 2024;63(9):2328-2335. doi:10.1093/rheumatology/kead665