Progression to Radiographic Axial Spondyloarthritis: A Narrative Review on Timeline and Novel Prediction Factors

Spondyloarthritis represents a group of chronic immune-mediated rheumatic diseases that manifest as peripheral or axial musculoskeletal involvement. In axial spondyloarthritis (axSpA), the milestones of structural damage are represented by inflammation, followed by erosions in the sacroiliac joints (SIJ) and new bone formation. The purpose of this narrative review is to address the unmet needs regarding targeted risk stratification of disease progression in axSpA. While studies concerning predictive biomarkers have been conducted, their use in clinical practice has not yet been validated. Analysis of disease progression in patients recently diagnosed with non-radiographic axSpA, with fulfillment of the Assessment of Spondyloarthritis International Society criteria, determined a mean time of structural changes progression of 2.4 years. While factors such as human leukocyte antigen (HLA)-B27 and C-reactive protein are useful in classifying patients into risk categories regarding radiographic progression, novel biomarkers are needed in clinical practice to further facilitate treatment strategy selection. Choosing biomarkers to analyze the potential of both spinal and SIJ radiographic progression is useful in monitoring patients and reducing the burden of disease. Fetuin-A, sclerostin, and autoantibodies against Cluster of Differentiation 74 (anti-CD74) were associated with SIJ changes in various studies. Regarding spinal structural damage, adipokines, particularly leptin and visfatin, have been extensively studied and have shown promising results. Dickkopf-1, a regulator of the Wnt signaling pathway, vascular endothelial growth factor, and matrix metalloproteinase-3 have also presented associations with worsening modified Stoke Ankylosing Spondylitis Spine Score. The potential of each biomarker may be heightened by their use in prediction models with the purpose of implementation in clinical practice, particularly in improving patient outcomes and tailoring treatment strategies for individuals with spinal structural damage.