There are some data available on the frequency of structural damage in the spine in patients with ankylosing spondylitis (AS) and about potential risk factors for the development of syndesmophytes, but these data refer exclusively to patients with longstanding AS. Nearly no data exist regarding rates and predictors of radiographic spinal progression in early axial spondyloarthritis (SpA). The objective of the study was to investigate rates and predictors of structural damage development in the spine in patients with early axial SpA (AS with symptoms duration of <10 years and non-radiographic axial SpA (nrSpA) with symptoms duration of <5 years).
210 patients with axial SpA (115 with AS according to the modified New York criteria and 95 with nrSpA) from the German Spondyloarthritis Inception Cohort (GESPIC) were selected for this analysis based on availability of radiographs (sacroiliac joints, lumbar and cervical spine lateral views) at baseline and after 2 years of follow-up. Images were centrally collected, digitized, and subsequently scored independently by two trained readers. Spinal radiographs were scored according to the mSASSS scoring system. The readers scored both time points simultaneously but were blinded for the time point and for all clinical data. Significant radiographic spinal progression was defined as a worsening of the mean mSASSS score by ≥2 units over two years
Altogether, 14.3% of the patients in the whole SpA group showed spinal radiographic progression according to this definition. This rate was higher in the group of patients with AS (20%) in comparison to non-radiographic axial SpA (7.4%). The following parameters were independently associated with radiographic spinal progression: presence of syndesmophytes at baseline (odds ratio (OR)=6.29, p<0.001), elevated markers of systemic inflammation (erythrocyte sedimentation rate: OR=4.04, p=0.001, C-reactive protein: OR=3.81, p=0.001), and cigarette smoking (OR=2.75, p=0.012), that was confirmed in the multivariate logistic regression analysis. No clear association with radiographic spinal progression was found for HLA-B27 status, sex, age, disease duration, BASDAI, BASFI, presence of peripheral arthritis, enthesitis or psoriasis. Based on the obtained data two prediction matrix models were constructed incorporating the following variables: baseline syndesmophytes, smoking status and an elevated acute phase reactant (either ESR or CRP) – figure.
The presence of radiographic damage in the spine (syndesmophytes), elevated acute phase reactants and cigarette smoking status predict spinal radiographic progression in early axial SpA.
Disclosure: D. Poddubnyy, None; H. Haibel, None; J. Listing, None; E. Märker-Hermann, None; H. Zeidler, None; J. Braun, None; J. Sieper, None; M. Rudwaleit, None.