Background Cigarette smoking has been associated with functional impairment [1, 2] and radiographic severity of ankylosing spondylitis (AS) [3, 4]. Moreover, smoking status at baseline was found recently to be an independent predictor of radiographic spinal progression in the whole group of axial spondyloarthritis (SpA) . However, it is not clear whether smoking intensity plays a role as a factor predicting radiographic progression in the spine.
Objectives The objective of the current analysis was to investigate the relationship between smoking intensity and radiographic spinal progression in patients with axial SpA.
Methods In total, 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 of spinal radiographs at baseline and after 2 years of follow-up. Spinal radiographs were centrally collected, digitized, and subsequently scored according to the mSASSS independently by two trained readers, who were blinded for time point and all clinical data. Smoking status and smoking intensity (non-smoker, 10 cigarettes a day and less, 11 to 20 cigarettes, and more than 20 cigarettes a day) was assessed retrospectively every 6 months during 2 years of follow-up.
Results 139 patients (66.2%) were considered to be non-smokers throughout the entire follow-up period of 2 years, 43 patients (20.5%) smoked 10 cigarettes a day and less (as a mean over two years), 22 patients (10.5%) smoked 11-20 cigarettes and only 6 patients (2.9%) smoked more than 20 cigarettes a day and, therefore, were pooled with the group of 11-20 cigarettes a day. The mean mSASSS change over 2 years was 0.52±1.72 in non-smokers vs. 0.47±1.48 in a ≤10 cigarettes/day group (p=0.30) vs. 2.2±4.6 in >10 cigarettes/day group (p=0.077 vs. non-smokers, p=0.35 vs. ≤10 cigarettes/day group). Significant radiographic progression (defined as an mSASSS worsening by 2 units and more over 2 years) was observed in 10.1% of non-smokers vs. 18.6% in whose who smoked up to 10 cigarettes a day (odds ratio (OR)=2.0, 95%CI 0.8-5.3, p=0.14). In patients who smoked more than 10 cigarettes a day, significant radiographic progression was seen in 28.6% of the cases resulting in OR=3.6, 95%CI 1.3-9.6, p=0.012 versus non-smoking.
Conclusions Tobacco smoking has a clear dose-dependent effect on radiographic spinal progression in axial SpA with the highest progression risk in whose patients who smoke more than 10 cigarettes a day.
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Disclosure of Interest None Declared