Harmonizing factor assay-related testing performed in a large laboratory network.

Coagulation factor testing is commonly performed within haemostasis laboratories, either to assess for bleeding disorders, such as haemophilia, or to investigate unexplained prolongation in routine coagulation assays. The aim of this evaluation was to harmonize procedures and normal reference ranges (NRRs) for investigation of coagulation factors on the ACL TOP 50 family of instruments in a large laboratory network. We employed comparative evaluations using newly installed ACL TOPs 550 and 750 and HemosIL reagents vs. existing 'reference' instrumentation and reagents, predominantly Stago and Siemens, as well as assessment of factor sensitivity in routine coagulation assays, prothrombin time (PT) and activated partial thromboplastin time (APTT). Also, establishment of coagulation factor NRRs using normal plasma samples. HemosIL factor assays showed good comparability with the existing reference methods ( R > 0.9). Factor sensitivity for PT and APTT assays were acceptable at around 30 U/dl. NRRs were established and harmonized across the laboratory network. This evaluation of factor testing on ACL TOP 50 Family instruments identified overall acceptable performance using Werfen reagents and enabled harmonization of coagulation factor testing in our large network.

Emicizumab assay evaluations and results from an Australian field study of emicizumab measurement.

Emicizumab is a recombinant, humanised bispecific antibody which acts as a FVIII mimetic and is a therapeutic option for haemophilia A. Plasma emicizumab levels may sometimes be required. Multiple one-stage clotting assays (OSA) and one human component chromogenic assay (CSA) were used to measure emicizumab both centrally and by a field study. The study samples drug concentrations range included within therapy range of 35-70 µg/mL. All assays were modified from traditional FVIII assays to enable replacement of plasma calibrators with emicizumab calibrators. Central laboratory OSA mean recovery levels (target) for six spike levels of emicizumab were close to target at 120.5 (120), 81.6 (80), 40.9 (40), 21.4 (20), 10.7 (10) and 5.5 (5) µg/mL. Field study OSA mean recoveries were similarly close to target. Between method coefficients of variation were <9% in both the central laboratory and field study assays, except for the 5 µg/mL sample which was 12.3%. CSA mean recoveries were within 10% of target at 80, 50 and 20 µg/mL levels. This study affirms that emicizumab can be measured by OSA using many types of activated partial thromboplastin time (APTT) reagents and is also measurable by the human CSA. The assays showed good precision, accuracy and linearity both locally and in a field study setting.

A multi-laboratory assessment of lupus anticoagulant assays performed on the ACL TOP 50 family for harmonized testing in a large laboratory network.

INTRODUCTION: Lupus anticoagulant (LA) testing is commonly performed within hemostasis laboratories, and the ACL TOP 50 family of instruments represent a new "single platform" of hemostasis instrumentation. Our aim was to evaluate these instruments and manufacturer reagents or alternatives for utility in LA testing. METHODS: Comparative evaluations of LA testing using newly installed ACL TOPs 550 and 750 as well as comparative assessments with existing "reference," predominantly Stago, instrumentation, and reagents. Evaluations comprised both dilute Russell viper venom time (dRVVT) and activated partial thromboplastin time (APTT)-based assays. Establishment of normal reference ranges (NRR). RESULTS: The HemosIL dRVVT-based assays showed good comparability with the existing Stago reference method (R > 0.9) and could be considered as verified as fit for purpose. A variety of APTT assays was additionally evaluated for LA utility, and we identified from the assessment good utility of a non-Werfen solution in Hyphen BioMed Cephen reagents. NRR were established based on ≥120 normal individual plasma samples. CONCLUSION: This evaluation of LA reagents on ACL TOP 50 Family instruments identified overall acceptable performance of both dRVVT (Werfen solution) and APTT (non-Werfen solution) to enable harmonization of LA testing in our large network.

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.

OBJECTIVES: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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).

Hemostasis, coagulation and thrombin in venoarterial and venovenous extracorporeal membrane oxygenation: the HECTIC study.

Extracorporeal membrane oxygenation (ECMO) support has a high incidence of both bleeding and thrombotic complications. Despite clear differences in patient characteristics and pathologies between veno-venous (VV) and veno-arterial (VA) ECMO support, anticoagulation practices are often the same across modalities. Moreover, there is very little data on their respective coagulation profiles and comparisons of thrombin generation in these patients. This study compares the coagulation profile and thrombin generation between patients supported with either VV and VA ECMO. A prospective cohort study of patients undergoing VA and VV ECMO at an Intensive care department of a university hospital and ECMO referral centre. In addition to routine coagulation testing and heparin monitoring per unit protocol, thromboelastography (TEG), multiplate aggregometry (MEA), calibrated automated thrombinography (CAT) and von-Willebrand's activity (antigen and activity ratio) were sampled second-daily for 1 week, then weekly thereafter. VA patients had significantly lower platelets counts, fibrinogen, anti-thrombin and clot strength with higher d-dimer levels than VV patients, consistent with a more pronounced consumptive coagulopathy. Thrombin generation was higher in VA than VV patients, and the heparin dose required to suppress thrombin generation was lower in VA patients. There were no significant differences in total bleeding or thrombotic event rates between VV and VA patients when adjusted for days on extracorporeal support. VA patients received a lower median daily heparin dose 8500 IU [IQR 2500-24000] versus VV 28,800 IU [IQR 17,300-40,800.00]; < 0.001. Twenty-eight patients (72%) survived to hospital discharge; comprising 53% of VA patients and 77% of VV patients. Significant differences between the coagulation profiles of VA and VV patients exist, and anticoagulation strategies for patients of these modalities should be different. Further research into the development of tailored anticoagulation strategies that include the mode of ECMO support need to be completed.

Verification of the ACL Top 50 Family (350, 550, and 750) for Harmonization of Routine Coagulation Assays in a Large Network of 60 Laboratories.

OBJECTIVES: To verify a single platform of hemostasis instrumentation, the ACL TOP 50 Family, comprising 350, 550, and 750 instruments, across a large network of 60 laboratories. METHODS: Comparative evaluations of instrument classes (350 vs 550 and 750) were performed using a large battery of test samples for routine coagulation tests, comprising prothrombin time/international normalized ratio, activated partial thromboplastin time (APTT), thrombin time, fibrinogen and D-dimer, and using HemosIL reagents. Comparisons were also made against existing equipment (Diagnostica Stago Satellite, Compact, and STA-R Evolution) and existing reagents to satisfy national accreditation standards. Verification of manufacturer normal reference ranges (NRRs) and generation of an APTT heparin therapeutic range were undertaken. RESULTS: The three instrument types were verified as a single instrument class, which will permit standardization of methods and NRRs across all instruments (n = 75) to be deployed in 60 laboratories. In particular, ACL TOP 350 test result data were similar to ACL TOP 550 and 750 and showed no to limited bias. All manufacturer NRRs were verified with occasional minor variance. CONCLUSIONS: This ACL TOP 50 Family (350, 550, and 750) verification will enable harmonization of routine coagulation across all laboratories in the largest public pathology network in Australia.