THU0278 Serum calprotectin is correlated with disease activity in early axial spondyloarthritis but does not predict radiographic progression at 2 years: results from the desir cohort
Authors: X. Romand, M.H. Paclet, A. Courtier, M.-V.-C. Nguyen, F. Berenbaum, D. Wendling, P. Gaudin, A. Baillet
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Calprotectin (S100A8/A9), a protein secreted by activated neutrophils and monocytes in inflammatory conditions, is upregulated in active spondyloarthritis<sup><sup>1</sup></sup> and associated with radiographic spinal progression in axial spondyloarthritis (axSpA)<sup><sup>2</sup></sup> <h3>Objectives</h3> To determine if serum calprotectin level at baseline can predict the radiographic progression of structural damage in spine at 2 years in the early axSpA cohort DESIR (DEvenir des Spondyloarthrites Indifférenciées Récentes) and to compare the association with spine and sacroiliac joint (SIJ) inflammation on magnetic resonance imaging (MRI). <h3>Methods</h3> Patients presenting with inflammatory back pain suggestive of axSpA for less than 3 years from the DESIR cohort were analysed. axSpA patient were defined as patients who fulfilled the Assessment in SpondyloArthritis Society (ASAS) criteria for axSpA at baseline. Calprotectin was assessed in the serum at baseline with ELISA kit (Hycult Biotech, the Netherlands). Spine radiographs, SIJ and spine MRI were centrally scored. Radiographic spinal progression was defined as worsening by ≥2 units of the mSASSS 2 years after the inclusion. Level of MRI spine and SIJ inflammation at baseline and 2 years was evaluated with BERLIN and SPARCC score. The associations between calprotectin level and mSASSS worsening were tested with Wilcoxon test, Berlin and SPARCC score were tested by Spearman's correlation tests. <h3>Results</h3> Of all, 426 had a calprotectin dosage and an early axSpA according to the ASAS criteria. Among them, 211patients have had a mSASSS scoring at baseline and M24. A total of 399 patients have had spinal and SIJ MRI scoring at baseline. Only 15 patients had a radiographic progression with a variation of mSASSS ≥2. We showed a correlation between baseline calprotectin and MRI inflammation in SIJ or spine (Berlin score (r=0.15, p=0.003), SPARCC Sacroiliac score (r=0.12, p=0.012) and SPARCC Spine score (r=0.16, p=0.002)). Calprotectin baseline level was significantly higher in patients who fulfilled axSpA ASAS sacroiliitis arm criteria versus those who fulfilled ASAS HLA B27 arm criteria without any signs of sacroiliitis or versus patients did not fulfil ASAS criteria (respectively p&lt;0,001, p=0,004). Calprotectin level was correlated with baseline disease activity index (BASDAI (r=0.16, p=0.001), ASDAS-CRP (r=0.26, p&lt;0.001)) and disability score (BASFI (r=0.14, p=0,003), ASQoL (r=0.16, p=0.001)). Interestingly, calprotectin at baseline did not predict radiographic progression at M24 (mSASSS worsening 0,27 µg/mL ±0,14 vs without mSASSS worsening 0,29 µg/mL ±0,19 (mean±SD)). There was also no correlation between calprotectin level and number of syndesmophytes. <h3>Conclusions</h3> Calprotectin do not seem to be a helpful biomarker predicting clinically relevant radiographic progression at 2 years although calprotectin levels at baseline are moderately correlated with disease activity in early axSpA. <h3>References</h3> [1] Gupta L, et al. Clinical Rheumatology2016. [2] Turina MC, et al. Ann Rheum Dis2014. <h3>Disclosure of Interest</h3> None declared