Non-radiographic axial spondyloarthritis in Tunisia: main characteristics and detailed comparison with ankylosing spondylitis

Objectives The aim of the present study is to compare the clinical features, disease activity, and physical impairment between non-radiographic axial spondyloarthritis and ankylosing spondylitis in Tunisian patients. Methods This is a retrospective study conducted in a single rheumatology center in Tunisia. Patients with axial spondyloarthritis fulfilling the 2009 ASAS criteria were included. The various spondyloarthritis-related variables were compared between non-radiographic axial spondyloarthritis and ankylosing spondylitis. p Values below 0.05 were considered statistically significant. Results Among 200 patients with axial spondyloarthritis, 40 had non-radiographic axial spondyloarthritis and 160 had ankylosing spondylitis. The non-radiographic axial spondyloarthritis patients were more frequently female, were younger, and had shorter disease duration. Patients with non-radiographic axial spondyloarthritis experienced enthesitis more frequently compared with ankylosing spondylitis patients. Psoriasis was more frequent in non-radiographic axial spondyloarthritis group, while inflammatory bowel disease was more frequent in ankylosing spondylitis group. The C-reactive protein level and functional score were significantly higher in patients with ankylosing spondylitis compared with non-radiographic axial spondyloarthritis. Tumor necrosis factor inhibitors were offered significantly more often to the ankylosing spondylitis group. There was no statistically significant difference between the 2 groups in other spondyloarthritis parameters. Conclusion The non-radiographic axial spondyloarthritis is characterized mainly by a marked female prevalence, a higher enthesitis prevalence, and a better physical function. Key points: • Patients with nr-axSpA in Tunisia are more frequently female and have shorter disease duration compared with those with AS. • Peripheral manifestations were similar between nr-axSpA and AS patients except for enthesitis which were more frequent within nr-axSpA patients. • The disease activity is similar between the 2 groups of axSpA but the physical function is better within nr-axSpA patients.