A3.10 Serum calprotectinis elevated in patients with early rheumatoid arthritis but not in patients at risk of developing rheumatoid arthritis

Background and objectives Calprotectin( S100A8/ S100A9complex) is associated with disease activity, radiographic progression and may predict treatment response in patients with rheumatoid arthritis (RA). The aim of our study was to examine the serum levels of calprotectinin clinically suspect arthralgia patientswith positive antibodies to citrullinatedpeptide antigens (ACPA) who areat high risk of developing RA. Materials and methods This cross-sectional study included 20 ACPA+ arthralgiapatients, 55 patients with early RA (disease duration Results Patients with clinically suspect arthralgia showed no clinical and ultrasound evidence of arthritis (grey scale and power Doppler for single joint ≤ 1). Of these, all were ACPA+, 70%females; age 41.92 ± 11.72 years, CRP 7.39 ± 19.19 mg/l. Treatment naive patients with early RA had active disease (meanDAS28:5.54 ± 1.62), 65% were ACPA+, 71% were females; age 54.17 ± 16.77 years and CRP 20.46 ± 26.66 mg/l. Serum calprotectinin clinically suspect ACPA+ arthralgia patientswas not significantly different compared to HC (2980 ± 1610 vs. 3368 ± 1624 ng/ml, p = 0.35) but was significantly lower in both groups compared to early RA (5977 ± 5787 ng/ml, p = 0.01 and 0.02 respectively). There was no correlation between calprotectinand CRP in suspect arthralgia patients, however, in early RA, serum calprotectinsignificantly correlated with DAS28 (r = 0.432, p = 0.001) and CRP (r = 0.670, p Conclusions Calprotectinis not increased in ACPA positive patients who have normal ultrasound findings of small joints and thus may not help to predict RA development in this early stage of the disease. However, calprotectinis significantly elevated in patients with active early RA, where it serves as a reliable biomarker of disease activity. Acknowledgements IGA project no. NT 14498, project of MHCR 023728 and project SVV 260 155.