Background Ankylosing spondylitis (AS) is a chronic inflammatory, rheumatic disease predominately affecting the axial skeleton. It is a slowly progressing disease which can be described by excessive connective tissue remodelling. Early identification of progression is needed in order to target and slow disease progression prior to joint destruction. The excessive connective tissue remodelling can be assessed by serum quantification of type I collagen degradation fragments (C1M) generated by matrix metalloproteinase, which has shown to be a biomarker of disease progression in RA1.
Objectives We investigated the relationship between the serum measure of C1M and radiographic progression in AS and possible interactions with co-variants.
Methods Patients in the Outcome in Ankylosing Spondylitis international Study (OASIS, n=122) with serum available and with a 2-year radiographic progression score were included in this study. Radiographic progression was measured as the difference in the modified Stoke in AS (mSASSS) between the two radiographs. C1M2 was assessed in serum at baseline. Linear regression analyses were conducted, adjusted for potential confounders (table). Interactions were tested.
Results The studied population consisted of 70% male with a mean symptom duration of 23 years (SD 12), 82% were HLA-B27 positive and 91% were anti-TNF naïve. Baseline C1M was significantly predictive of 2-year mSASSS progression (β 0.01, p=0.050). This effect disappeared when adjusted for confounders. However, C1M as predictor of progression was different in smokers and non-smokers. In smokers, the effect was more pronounced (unadjusted: β 0.01, p=0.003 and adjusted: β 0.06, p=0.019). Interestingly, C1M was a better predictor of progression in patients with a disease duration of less than 18 years (p=0.016). The effect of C1M on radiographic progression disappeared when CRP was included in the model.
Conclusions C1M is a potential biomarker of radiographic progression in AS, particularly in patients who smoke and who have shorter disease duration. However, C1M seems to predict progression as much as CRP. This suggests that C1M could be a biomarker that can identify fast progressors in AS.
Siebuhr AS et al. 2013, ART, 15:R86 doi:10.1186/ar4266. 2: Leeming,D. et al. 2011, Biomarkers 16, 616-628 (2011).
Disclosure of Interest A. S. Siebuhr Employee of: Nordic Bioscience, S. Ramiro: None declared, A.-C. Bay-Jensen Employee of: Nordic Bioscience, D. van der Heijde: None declared, R. Landewé: None declared, A. Tubergen: None declared, M. Karsdag Shareholder of: Nordic Bioscience, Employee of: Nordic Bioscience
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