The Prevalence of Non-radiographic Axial Spondyloarthritis Among Patients with Inflammatory Back Pain from Northwest and South Africa: Data from a Noninterventional, Cross-Sectional Study

INTRODUCTION: Information is limited on the prevalence and clinical characteristics of nonradiographic axial spondyloarthritis (nr-axSpA) among patients with inflammatory back pain (IBP) in African countries. A global study estimated the prevalence of nr-axSpA among patients with IBP from 19 countries in Latin America, Europe, Asia, and Africa. This post hoc subset analysis focused on estimating prevalence of nr-axSpA and clinical characteristics among patients with IBP from Northwest Africa (Morocco and Algeria) and South Africa. METHODS: Patients from Northwest Africa and South Africa diagnosed with nr-axSpA according to protocol completed patient-reported outcome measures to assess disease activity and functional limitations, including Ankylosing Spondylitis Disease Activity Score (ASDAS). RESULTS: Of the 206 patients with IBP from Africa (n = 168, Northwest Africa and n = 38, South Africa), 33 (16.0%) were diagnosed with nr-axSpA (n = 26, Northwest Africa and n = 7, South Africa), corresponding to prevalence rates of 15.5% and 18.4%, respectively. Disease activity per region, measured as mean ASDAS, was 2.4 ± 1.4 and 2.4 ± 0.9, respectively, based on erythrocyte sedimentation rate and 2.4 ± 1.3 and 2.7 ± 0.7 based on C-reactive protein. CONCLUSIONS: Although the number of patients available for the analysis was low, it appears that the prevalence of nr-axSpA among patients with IBP is similar between Northwest and South Africa, and the disease burden is substantial. Limited access to magnetic resonance imaging may hinder early detection in these areas, thereby affecting the assessment of prevalence. FUNDING: Pfizer.