In patients receiving TNF-α inhibitors (TNFi) for ankylosing spondylitis (AS), serum levels of biomarkers at baseline can predict radiographic spinal progression over 2 and 4 years, independent of recognized risk factors.

• This study included 137 AS patients from the Groningen Leeuwarden Axial Spondyloarthritis (GLAS) cohort before starting TNFi, and serum biomarkers were assessed at baseline, 3 months and 2 years.

• Baseline calprotectin and visfatin concentrations were found to be linked with mSASSS progression ≥2 points (OR 1.195 and 1.465, respectively), while calprotectin was also identified to be linked with new syndesmophyte formation after 2 years (OR 1.107).

• Progression of mSASSS ≥4 points after 4 years was related to baseline leptin level (OR 0.614), and baseline sCTX (serum C-terminal telopeptide fragments of type I collagen) level was associated with syndesmophyte formation post-4 years (OR 1.004).

• Furthermore, alteration of visfatin and leptin concentrations over the first 2 years demonstrated significant link with radiographic progression following 4 years.