Epidemiology of spondyloarthritis in Argentina

Spondyloarthritis (SpA) includes a group of diseases that share immunogenetic, clinical and radiologic findings, with a particular involvement of the axial skeleton and the entheses.

SpA patients attending ambulatory care in 11 rheumatology services located in 6 Argentine provinces were included in a prospective, observational multicentre cohort of SpA in Argentina (Iberoamerican Spondyloarthritis Registry [RESPONDIA]). Data collected were transmitted online and stored in the Spanish spondyloarthritis registry (REGISPONSER) Web site. Sociodemographic, clinical features and diagnosis, disease activity, functional status, quality of life, work status, radiographic changes and treatment data were collected by means of validated tools.

A total of 402 patients were included; 59% were male, with median age of 48.3 years and median disease duration of 8 years; 68.7% of patients belonged to middle and lower-middle social classes. Eighty-six patients were diagnosed with ankylosing spondylitis (AS), 242 with psoriatic arthritis, 25 with reactive arthritis, 10 with SpA associated with inflammatory bowel disease, 33 with undifferentiated SpA and 6 with juvenile AS. The median score was 2.6 for the Bath AS Functional Index, 3.8 for the Bath AS Disease Activity Index and 5 for the Bath AS Radiology Index. The lower social class patients achieved a worse Bath AS Functional Index than other social classes and a worse Bath AS Disease Activity Index, compared with upper-middle class.

The sociodemographic distribution pattern observed in these SpA patients was similar to that expected in the general population of Argentina, with worse functional capacity and higher disease activity observed in the lower social classes.