Article
Calprotectin serum level independently predicts radiographic spinal progression in axial spondyloarthritis
Search Medline for
Authors
Published: | September 12, 2014 |
---|
Outline
Text
Background: It has been shown previously that markers of systemic inflammation (i.e., elevated C-reactive protein – CRP) are independently associated with radiographic spinal progression over two years in patients with axial spondyloarthritis (axSpA) in the German Spondyloarthritis Inception Cohort (GESPIC). Calprotectin, a heterodimer of the calcium binding proteins S100A8 and S100A9, is secreted during monocyte infiltration into inflamed tissues and thus directly reflects a potentially important pathophysiological mechanism in SpA. The aim of this study was to determine the predictive value of serum calprotectin for radiographic spinal progression in axSpA.
Methods: Seventy six patients with definite axSpA from GESPIC were selected for this analysis. Radiographic spinal progression after 2 years of follow up was defined as 1) worsening of the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) by ≥2 units, and 2) development of a new syndesmophyte or progression of existing syndesmophytes (formation of a bridging syndesmophyte). Levels of serum calprotectin were determined by ELISA at baseline.
Results: Baseline calprotectin serum values were higher in patients with mSASSS worsening by ≥2 units after 2 years (n=15) versus those without progression (0.68±0.21 vs. 0.48±0.26 μg/ml, respectively, p=0.005) and in patients with syndesmophyte formation (n=18) versus those without new bone formation (0.64±0.27 vs. 0.48±0.25 μg/ml, respectively, p = 0.035). A receiver operating characteristic (ROC)-analysis showed a good performance of calprotectin in prediction of mSASSS worsening, as well as in prediction of syndesmophyte formation/progression-figure. Calprotectin serum level >0.5 μg/ml had a sensitivity of 80% and specificity of 62% as predictor of mSASSS worsening with an odds ratio (OR)=6.2 (95% CI 1.6-24.2). As predictor of syndesmophytes formation, calprotectin serum level >0.5 μg/ml demonstrated a sensitivity of 72%, a specificity of 60%, and an OR=4.1 (95% CI 1.2-32.0). These associations remained significant after adjustment for other known risk factors for radiographic spinal progression including syndesmophytes, CRP and smoking (Figure 1 [Fig. 1]).
Conclusion: Calprotectin is a biomarker with an independent predictive value for radiographic spinal progression in axSpA.