A multi-laboratory assessment of congenital thrombophilia assays performed on the ACL Top 50 family for harmonisation of thrombophilia testing in a large laboratory network

Thrombophilia testing is commonly performed within hemostasis laboratories, and the ACL TOP 50 family of instruments represent a new 'single platform' of hemostasis instrumentation. The study objective was to evaluate these instruments and manufacturer reagents for utility of congenital thrombophilia assays. Comparative evaluations of various congenital thrombophilia assays (protein C [PC], protein S [PS], antithrombin [AT], activated protein C resistance [APCR]) using newly installed ACL TOPs 550 and 750 as well as comparative assessments with existing, predominantly STAGO, instrumentation and reagents. Verification of manufacturer assay normal reference ranges (NRRs). HemosIL PC and free PS assays showed good comparability with existing Stago methods (R>0.9) and could be considered as verified as fit for purpose. HemosIL AT showed high relative bias with samples from patients on direct anti-Xa agents, compromising utility. Manufacturer NRRs for PC, PS and AT were verified with minor variance. Given the interference with direct anti-Xa agents, an alternate assay (Hyphen) was evaluated for AT, and the NRR also verified. The HemosIL Factor V Leiden (APC Resistance V) evidenced relatively poor performance compared to existing assays, and could not be adopted for use in our network. This evaluation of HemosIL reagents on ACL TOP 50 Family instruments identified overall acceptable performance of only two (PC, free PS) of four thrombophilia assays, requiring use of third-party reagents on ACL instruments for the other two assays (AT, APCR).