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Abstract
Background ACPA finds its place in early RA diagnosis. Improvements are made in measurement of ACPA with recently designed fluorescent-based microparticles immunoassay which allows the simultaneous detection of 4 anti-CCP autoantibody specificities: anti-HCP1, anti-HCP2, anti-VCP1 and anti-VCP2.
Objectives The aim of this work is to evaluate the performance of new anti-CCP multiplexing assay comparing to anti-CCP3 ELISA test.
Methods Detection and measurement of ACPA by FIDIS™ anti-CCP (Theradiag) multiplexing assay were compared to the anti-CCP3 ELISA (INOVA) in 171 [98 anti-CCP3 (+), 73 anti-CCP3 (-)] sera patients with early arthritis.
Results Global concordance was about 81% between FIDIS anti-CCP and anti-CCP3 (Table 1 and Table 2) while, for each of four FIDIS citrullinated peptides, this concordance is shown on Table 2.
We observed a good concordance between two tests. Otherwise, it is noteworthy that among anti-CCP3 (-) patients, 17 (23%) were FIDIS anti-CCP (+). Among them, 53% recognize 1 citrullinated peptide, 35% 2 peptides and 6% 3 or 4 peptides. Thus, the FIDIS anti-CCP test increases the sensitivity of detection of ACPA compared to anti-CCP3 that have proven good diagnostic performance. However, some specificities are not detected by the new method comparatively to anti-CCP3.
Conclusions FIDIS anti-CCP multiplexing assay shows good performance comparing to anti-CCP3 and must be assessed on larger series of patients with early RA compared to control populations.
References
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Disclosure of Interest None declared
DOI 10.1136/annrheumdis-2014-eular.6049