High disease activity according to the Ankylosing Spondylitis Disease Activity Score is associated with accelerated radiographic spinal progression in patients with early axial spondyloarthritis: results from the GErman SPondyloarthritis Inception Cohort

Objective The aim of this work was to investigate the association between disease activity measured by the Ankylosing Spondylitis Disease Activity Score (ASDAS) and radiographic spinal progression in patients with early axial spondyloarthritis (axSpA). Methods Altogether, 178 patients with definite axSpA (100 with ankylosing spondylitis and 78 with non-radiographic axSpA) were included. Spinal radiographs (baseline and year 2) were assessed according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and for the presence of syndesmophytes. Clinical and lab data were collected at baseline and every 6 months thereafter. Time-averaged (over 2 years) values of the C-reactive protein based ASDAS were calculated. Results There was a clear positive association between disease activity according to ASDAS and radiographic spinal progression. In the logistic regression analysis, mSASSS progression by >= 2 points over 2 years was significantly associated with the time-averaged ASDAS: unadjusted OR=1.64 (95% CI 1.03 to 2.62), adjusted (for presence of syndesmophytes at baseline, smoking status and intake of non-steroidal anti-inflammatory drugs) OR=1.80 (95% CI 1.04 to 3.13). Syndesmophyte formation/progression demonstrated an even stronger association with the time-averaged ASDAS: unadjusted OR=2.62 (95% CI 1.46 to 4.68), adjusted OR=2.45 (95% CI 1.26 to 4.77). Conclusions Persisting high disease activity according to the ASDAS is associated with accelerated radiographic spinal progression in early axSpA.