Baseline radiographic damage, elevated acute‐phase reactant levels, and cigarette smoking status predict spinal radiographic progression in early axial spondylarthritis

OBJECTIVE: To assess prospectively the rates and to explore predictors of spinal radiographic progression over 2 years in a cohort of patients with early axial spondylarthritis (SpA). METHODS: Two hundred ten patients with axial SpA from the German Spondyloarthritis Inception Cohort were selected for this analysis based on the availability of radiographs at baseline and after 2 years of followup. Spinal radiographs were scored by 2 trained readers in a blinded, randomly selected order according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Spinal radiographic progression was defined as worsening of the mean mSASSS by ≥2 units over 2 years. RESULTS: Among the patients with axial SpA, 14.3% showed spinal radiographic progression after 2 years (20% of those with AS and 7.4% of those with nonradiographic axial SpA). The following parameters were independently associated with spinal radiographic progression: presence of syndesmophytes at baseline (odds ratio OR 6.29, P < 0.001), elevated levels of markers of systemic inflammation (for the erythrocyte sedimentation rate, OR 4.04, P = 0.001; for C-reactive protein level time-averaged over 2 years, OR 3.81, P = 0.001), and cigarette smoking (OR 2.75, P = 0.012). These associations were confirmed by multivariate logistic regression analysis. No clear association with spinal radiographic progression was observed for HLA-B27 status, sex, age, disease duration, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, presence of peripheral arthritis, enthesitis, psoriasis, treatment with nonsteroidal antiinflammatory drugs, or treatment with disease-modifying antirheumatic drugs at baseline. CONCLUSION: The presence of radiographic damage at baseline (syndesmophytes), elevated levels of acute-phase reactants, and cigarette smoking were all independently associated with spinal radiographic progression in patients with early axial SpA.