Publications by authors named "Leonardo Pasalic"

43 Publications

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.

Clin Chem Lab Med 2021 Jun 14. Epub 2021 Jun 14.

Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.

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).
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http://dx.doi.org/10.1515/cclm-2021-0499DOI Listing
June 2021

Laboratory testing for ADAMTS13: Utility for TTP diagnosis/exclusion and beyond.

Am J Hematol 2021 May 15. Epub 2021 May 15.

Section of Clinical Biochemistry, University of Verona, Verona, Italy.

The metalloproteinase ADAMTS13 (a disintegrin with a thrombospondin type 1 motif, member 13), also known as VWF (von Willebrand factor) protease, may be assessed in a vast array of clinical conditions. Notably, a severe deficiency of ADAMTS13 characterizes TTP (thrombotic thrombocytopenic purpura), a rare but potentially fatal disorder associated with thrombosis due to accumulation of prothrombotic ultra-large VWF multimers. Although prompt identification/exclusion of TTP can be facilitated by rapid ADAMTS13 testing, the most commonly utilized assays are based on ELISA (enzyme linked immunosorbent assay) and require long turnaround time and have relatively limited throughput. Nevertheless, several rapid ADAMTS13 assays are now available, at least in select geographies. The current mini-review discusses these issues, as well as the potential utility of ADAMTS13 testing in a range of other conditions, including coronavirus disease 2019 (COVID-19).
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http://dx.doi.org/10.1002/ajh.26241DOI Listing
May 2021

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

Am J Clin Pathol 2021 Apr 23. Epub 2021 Apr 23.

Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead Hospital, Westmead, Australia.

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.
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http://dx.doi.org/10.1093/ajcp/aqab004DOI Listing
April 2021

A multicenter laboratory assessment of a new automated chemiluminescent assay for ADAMTS13 activity.

J Thromb Haemost 2021 02 21;19(2):417-428. Epub 2020 Nov 21.

Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.

Background: Thrombotic thrombocytopenic purpura (TTP) is a rare but potentially fatal disorder caused by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency. Prompt identification/exclusion of TTP can thus be facilitated by rapid ADAMTS13 testing. The most commonly utilized (enzyme-linked immunosorbent assay [ELISA]-based) assay takes several hours to perform and so does not generally permit rapid testing.

Objectives: To evaluate the utility of a new automated test for ADAMTS13 activity, the HemosIL AcuStar ADAMTS13 Activity assay, based on chemiluminescence and able to be performed on an ACL AcuStar instrument within 33 minutes.

Patients/methods: This multicenter (n = 8) assessment included testing of more than 700 test samples, with similar numbers of prospective (n = 348) and retrospective (n = 385) samples. The main comparator was the Technozym ADAMTS13 Activity ELISA. We also assessed comparative performance for detection of ADAMTS13 inhibitors using a Bethesda assay.

Results: Overall, the chemiluminescent assay yielded similar results to the comparator ELISA, albeit with slight negative bias. ADAMTS13 inhibitor detection was also comparable, albeit with slight positive bias with the AcuStar assay. Assay precision was similar with both assays, and we also verified assay normal reference ranges.

Conclusions: The HemosIL AcuStar ADAMTS13 Activity assay provided results rapidly, which were largely comparable with the Technozym ADAMTS13 Activity ELISA assay, albeit lower on average. Conversely, inhibitor levels tended to be identified at a higher level on average. Thus, the HemosIL AcuStar ADAMTS13 Activity assay provides a fast and accurate means to quantitate plasma levels of ADAMTS13 for TTP/ADAMTS13 identification/exclusion, and potentially also for other applications.
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http://dx.doi.org/10.1111/jth.15157DOI Listing
February 2021

A multicentre assessment of contemporary laboratory assays for heparin induced thrombocytopenia.

Pathology 2021 Feb 5;53(2):247-256. Epub 2020 Oct 5.

NSW Health Pathology, NSW, Australia; Prince of Wales Hospital, Randwick, NSW, Australia.

Heparin induced thrombocytopenia (HIT) is a rare but potentially fatal complication of heparin therapy. In some patients, HIT causes platelet activation and thrombosis (sometimes abbreviated HITT), which leads to adverse clinical sequalae ('pathological HIT'). The likelihood of HIT is initially assessed clinically, typically using a scoring system, of which the 4T score is that most utilised. Subsequent laboratory testing to confirm or exclude HIT facilitates exclusion or diagnosis and management. The current investigation comprises a multicentre (n=9) assessment of contemporary laboratory testing for HIT, as performed over the past 1-3 years in each site and comprising testing of over 1200 samples. The primary laboratory test used by study participants (n=8) comprised a chemiluminescence procedure (HIT-IgG) performed on an AcuStar instrument. Additional immunological testing performed by study sites included lateral flow (STiC, Stago), enzyme linked immunosorbent assay (ELISA), Asserachrom (HPIA IgG), PaGIA (BioRad), plus functional assays, primarily serotonin release assay (SRA) or platelet aggregation methods. The chemiluminescence procedure yielded a highly sensitive screening method for identifying functional HIT, given high area under the curve (AUC, generally ≥0.9) in a receiver operator characteristic (ROC) analysis against SRA as gold standard. ELISA testing resulted in lower ROC AUC scores (<0.8) and higher levels of false positives. Although there is clear association with the likelihood of HIT, the 4T score had less utility than literature suggests, and was comparable to a previous study reported by some of the authors.
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http://dx.doi.org/10.1016/j.pathol.2020.07.012DOI Listing
February 2021

Oral anticoagulation therapy: an update on usage, costs and associated risks.

Pathology 2020 Oct 1;52(6):736-741. Epub 2020 Aug 1.

Section of Clinical Biochemistry, University of Verona, Verona, Italy.

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http://dx.doi.org/10.1016/j.pathol.2020.05.006DOI Listing
October 2020

Platelets in Coronavirus Disease 2019.

Semin Thromb Hemost 2020 10 30;46(7):823-825. Epub 2020 Apr 30.

Thrombosis and Haemostasis Research Unit, Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.

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http://dx.doi.org/10.1055/s-0040-1710006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645810PMC
October 2020

Acquired Platelet Dysfunction-Laboratory and Clinical Implications.

Semin Thromb Hemost 2020 04 21;46(3):235-237. Epub 2020 Apr 21.

Department of Laboratory Hematology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Wales, Australia.

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http://dx.doi.org/10.1055/s-0040-1708826DOI Listing
April 2020

Immune-Mediated Thrombotic Thrombocytopenic Purpura: A Narrative Review of Diagnosis and Treatment in Adults.

Semin Thromb Hemost 2020 Apr 7;46(3):289-301. Epub 2020 Apr 7.

Sydney Medical School, University of Sydney, Sydney, Australia.

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and potentially lethal disease characterized by fragmentary hemolysis, moderate-to-severe thrombocytopenia, end-organ dysfunction, and severely reduced ADAMTS13 levels (< 10%). Survival in iTTP has improved significantly since the introduction of plasma exchange as standard therapy combined with immune suppression to address the underlying pathophysiology. A host of challenges remain including prompt recognition of the disease, treatment of the end-organ effects of the disease, improving the early mortality rate, significantly reducing the relapse rate as well as addressing refractory disease. Discussed in this narrative review of iTTP are the recent measures aimed at addressing these issues, including improvements in clinical prediction models, postremission maintenance approaches with early retreatment as well as the development of novel therapies.
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http://dx.doi.org/10.1055/s-0040-1708541DOI Listing
April 2020

Failure of platelet function analyser 200 to demonstrate clinical clopidogrel resistance in a patient undergoing intracranial vascular stenting.

BMJ Case Rep 2020 Mar 12;13(3). Epub 2020 Mar 12.

Neurosurgery, Westmead Hospital, Sydney, New South Wales, Australia.

A patient undergoes intracranial stent insertion for stent-assisted coiling of a basilar tip aneurysm and left middle cerebral artery aneurysm. A flow diverting stent is also placed across an anterior communicating artery aneurysm. Prior to the procedure, the patient takes dual antiplatelet medications, being aspirin and clopidogrel. Because of the concern regarding in-stent thrombus and thromboembolic complications related to intracranial stenting and the high rate of clopidogrel resistance, preoperative platelet function testing (PFT) was undertaken to ensure platelet inhibition. In this case, PFT was performed on a platelet function analyser which demonstrated platelet inhibition. Ten days following the procedure, the patient represented with thromboembolic stroke. Repeat PFT performed with whole blood impedance aggregometry and despite full medication compliance demonstrated clopidogrel resistance. Clopidogrel was then ceased and prasugrel commenced. This case demonstrates the importance of appropriate platelet inhibition in patients with intracranial stents and the controversy surrounding PFT.
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http://dx.doi.org/10.1136/bcr-2019-233947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7069294PMC
March 2020

Coagulation studies: achieving the right mix in a large laboratory network.

Pathology 2019 Dec 23;51(7):718-722. Epub 2019 Oct 23.

Department of Haematology, Westmead Hospital, Westmead, NSW, Australia; Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia; Sydney Centres for Thrombosis and Haemostasis, Westmead, NSW, Australia.

Basic coagulation tests, activated partial thromboplastin time (APTT), prothrombin time (PT) and the related international normalised ratio (INR), are performed frequently in hospital settings. From a laboratory perspective, unexpected abnormal results require further action; either informing the ordering clinician, or second line testing to determine the underlying cause. To streamline laboratory workflow, a new system of expert laboratory rules was implemented. The medical implications of this new laboratory system are evaluated here. The electronic ordering system was updated to mandate clinical information regarding the presence of an anticoagulant, or 'no anticoagulant'. When the PT or APTT were abnormal, and no anticoagulant was reported, second line testing was automatically performed. The second line tests performed were: mixing studies, fibrinogen and thrombin time. Any sample with a mixing study that did not completely correct, or fibrinogen <1.0 g/L, or INR >7.0, was flagged for clinical review by the laboratory haematology registrar. In a 17-month period there were 362,692 APTT, PT/INR and fibrinogen tests performed. Of these, 14,160 (3.9%) were abnormal with either no reported anticoagulant, or an unknown anticoagulant status. A total of 934 (0.3%) were referred for review by the haematology registrar. Three (<0.001%) cases received altered medical management as a result of the haematology registrar review. In hospital settings, most abnormal coagulation studies are anticipated by the ordering clinician. Unexpected abnormal coagulation results of clinical significance are rare. Automated second line coagulation testing and medical review improves laboratory workflow without compromising patient safety.
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http://dx.doi.org/10.1016/j.pathol.2019.07.006DOI Listing
December 2019

Recurrent fetal hydrops with maternal M alloimmunisation: not a benign condition.

BMJ Case Rep 2019 Jul 21;12(7). Epub 2019 Jul 21.

Westmead Institute for Maternal and Fetal Medicine, Westmead Hospital, Westmead, New South Wales, Australia.

Haemolytic disease of the fetus and newborn (HDFN) is associated with red cell antibodies. Anti-M usually results in a mild haemolysis and is rarely clinically significant. There is no established consensus on management of pregnancies with anti-M. A case of recurrent HDFN with maternal M alloimmunisation was identified at a tertiary hospital in Australia. We collected the patient and neonate's clinical and pathological data and interpreted the case with available literature. This is the first case in literature of recurrent fetal hydrops in the setting of M alloimmunisation. Neonate was delivered in a poor condition, intubated and admitted to the neonatal intensive care unit for ionotropic support, red cell transfusion and plasma transfusion for coagulopathy. Direct Coombs test was positive, confirming HDFN. Although anti-M rarely causes HDFN, accurate history, fetal surveillance and monitoring is essential for identification of fetal anaemia. Concurrent placental disease may increase fetal risk from anti-M antibodies.
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http://dx.doi.org/10.1136/bcr-2019-230552DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6664319PMC
July 2019

Development and implementation of an expert rule set for automated reflex testing and validation of routine coagulation tests in a large pathology network.

Int J Lab Hematol 2019 Oct 4;41(5):642-649. Epub 2019 Jul 4.

Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead Hospital, Westmead, New South Wales, Australia.

Introduction: Haemostasis laboratories play a critical role in diagnosis and treatment of individuals with bleeding or thrombotic disorders. Routine coagulation assays such as prothrombin time (PT)/ international normalized ratio (INR), and activated partial thromboplastin time (APTT), are used in monitoring of anticoagulant therapy, as provided for treatment/prevention of thromboembolic disease, and also inform on potential haemostasis dysfunction. Increasing pressure is applied on clinical laboratories to improve response (test turnaround) times, reduce error rates and standardize policies. To this end, we describe our experience with the development and implementation of an automated process for reflex testing and validation of routine coagulation test results in a large pathology network compromising 27 laboratories.

Methods: Custom-built expert rules were created to perform reflex testing and fully automate routine test validation. These rules were developed/implemented over a 15-month period, including 6 months for development/ testing and 9 months for training/implementation of >100 personnel at 27 sites.

Results: These rules have enabled adherence of standardized pre-analytical (sample integrity) checks, automated reflex decisions, automated verification and overall alignment of network practices. In addition, clinically significant results are immediately referred to haematologists. We report an improvement in test turnaround times, also reflecting savings in operator time.

Conclusion: The process was generally well received and generally beneficial to most laboratories in the network.
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http://dx.doi.org/10.1111/ijlh.13078DOI Listing
October 2019

Diagnosis and management of heparin-induced thrombocytopenia: a consensus statement from the Thrombosis and Haemostasis Society of Australia and New Zealand HIT Writing Group.

Med J Aust 2019 06 2;210(11):509-516. Epub 2019 Jun 2.

St George Hospital, Sydney, NSW.

Introduction: Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder that occurs following the administration of heparin and is caused by antibodies to platelet factor 4 and heparin. Diagnosis of HIT is essential to guide treatment strategies using non-heparin anticoagulants and to avoid unwanted and potential fatal thromboembolic complications. This consensus statement, formulated by members of the Thrombosis and Haemostasis Society of Australia and New Zealand, provides an update on HIT pathogenesis and guidance on the diagnosis and management of patients with suspected or confirmed HIT.

Main Recommendations: A 4Ts score is recommended for all patients with suspected HIT prior to laboratory testing. Further laboratory testing with a screening immunoassay or confirmatory functional assay is not recommended in individuals with a low 4Ts score. However, if there are missing or unreliable clinical data, then laboratory testing should be performed. A positive functional assay result confirms the diagnosis of HIT and should be performed to confirm a positive immunoassay result. Heparin exposure must be ceased in patients with suspected or confirmed HIT and initial treatment with a non-heparin alternative instituted. Non-heparin anticoagulants (danaparoid, argatroban, fondaparinux and bivalirudin) used to treat HIT should be given in therapeutic rather than prophylactic doses. Direct oral anticoagulants may be used in place of warfarin after patients with HIT have responded to alternative parenteral anticoagulants with platelet count recovery.

Changes In Management As A Result Of This Statement: These are the first Australasian recommendations for diagnosis and management of HIT, with a focus on locally available diagnostic assays and therapeutic options. The importance of examining both clinical and laboratory data in considering a diagnosis of HIT cannot be overstated.
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http://dx.doi.org/10.5694/mja2.50213DOI Listing
June 2019

Flow Cytometry Assessment of Procoagulant Platelets Using a Dithiol-Reactive Probe.

Methods Mol Biol 2019 ;1967:305-321

Platelet and Thrombosis Research Laboratory, ANZAC Research Institute, Sydney, NSW, Australia.

Flow cytometry assessment of platelets using the combination of GSAO [4-(N-(S-glutathionylacetyl)amino)phenylarsonous acid], a dithiol-reactive probe, and P-selectin, a platelet activation marker, is a novel and powerful assay in the identification and quantification of the procoagulant subpopulation of platelets that has the capacity to support thrombin generation. In this chapter, we provide the flow cytometry protocols aimed at the study of procoagulant platelets under resting and agonist-stimulated conditions in whole blood and washed platelets of both human and murine (mouse) samples.
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http://dx.doi.org/10.1007/978-1-4939-9187-7_20DOI Listing
November 2019

Laboratory testing for lupus anticoagulant (LA) in patients taking direct oral anticoagulants (DOACs): potential for false positives and false negatives.

Pathology 2019 Apr 18;51(3):292-300. Epub 2019 Jan 18.

Department of Laboratory Haematology, Institute of Clinical Pathology and Medical Research, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia; Sydney Centres for Thrombosis and Haemostasis, Sydney, NSW, Australia.

We and others have previously highlighted the potential problems with testing of lupus anticoagulants (LA) in patients on anticoagulant therapy, including most recently as related to the direct oral anticoagulants (DOACs). Thus, current DOACs in use (e.g., dabigatran, a direct thrombin inhibitor, and apixaban and rivaroxaban, both direct Xa inhibitors), affect a wide variety of coagulation assays, including those used in LA investigation. The Russell viper venom time (RVVT) assay in particular, key to the investigation of LA, is highly sensitive to DOACs. LA is a marker of thrombophilia, and patients who have had a thrombosis may be placed on a DOAC. Thus, there is a high likelihood that LA testing will be requested on patients whilst they are on DOACs. In the current report, we have assessed data from our facility for the past two and a half years for all LA tests performed by RVVT testing, and have evaluated this data with respect to patient anticoagulant status. In total, there were 7170 test requests for RVVT associated testing during the period of data capture. Most LA-RVVT screen results (5008; ∼70%) were within normal limits, thereby excluding LA by RVVT method in most of the patient cohort. All DOACs led to a prolongation in both RVVT screen and confirm assays. However, rivaroxaban affected the screen more than the confirm, leading to higher RVVT ratios, whereas apixaban affected the confirm more than the screen, leading to lower RVVT ratios. LA testing in the presence of DOACs also led to lower intra-patient consistency in LA test results. We conclude that ex-vivo data appears to confirm the potential for false positive (with rivaroxaban) and potential for false negative (with apixaban) identification of LA in patients on DOAC treatment. We also make some recommendations in regards to such testing.
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http://dx.doi.org/10.1016/j.pathol.2018.11.008DOI Listing
April 2019

Anticoagulation at the extremes of body weight: choices and dosing.

Expert Rev Hematol 2018 10 25;11(10):817-828. Epub 2018 Sep 25.

d Department of Clinical Haematology , Westmead Hospital , Westmead , Australia.

Introduction: The landscape of therapeutic anticoagulation has changed dramatically over the past decade, with availability of direct oral anticoagulants (DOACs), which inhibit factor Xa or thrombin. However, the optimal anticoagulant agent and dosing strategy for patients at both extremes of body weight has not been established for any anticoagulant, including DOACs, vitamin K antagonists (VKA), and the various heparin options. Areas covered: This paper reviews available evidence to assist clinicians in prescribing of anticoagulation therapy at the extremes of body weight. Expert commentary: There are limited data to guide prescribing of all available anticoagulants at the extremes of weight and further research regarding efficacy and safety outcomes in these groups is required. Laboratory monitoring to guide dosing of traditional anticoagulants provides reassurance of 'predictable' efficacy. In contrast agents that are not routinely monitored by laboratory testing provide greater challenges. For example, underweight patients are at risk of receiving higher drug exposures of DOACs, whereas the use of fixed dose DOACs in obese patients may be associated with lower drug exposures.
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http://dx.doi.org/10.1080/17474086.2018.1517040DOI Listing
October 2018

Lessons learnt from local real-life experience with idarucizumab for the reversal of dabigatran.

Intern Med J 2019 Jan;49(1):59-65

Department of Haematology, Westmead Hospital, Sydney, New South Wales, Australia.

Background: Idarucizumab is a specific antidote for the direct thrombin inhibitor oral anticoagulant dabigatran etexilate. It has been used with increasing frequency in Australia since it was granted Therapeutic Goods Administration approval in October 2016.

Aims: To assess idarucizumab usage, effect on coagulation parameters and clinical outcomes in patients who received idarucizumab in Western Sydney Local Health District (WSLHD).

Methods: A retrospective audit was conducted of all patients who received idarucizumab in WSLHD between September 2015 and December 2017.

Results: Of the 23 patients who received idarucizumab, 17 (74%) had bleeding, and 6 (26%) required urgent surgery/procedure. Thrombin time (TT) or activated partial thromboplastin time (APTT, when TT not available) remained prolonged at 24 h post-idarucizumab infusion in 10 of 20 (50%) patients. Renal impairment at admission was associated with prolonged TT/APTT at 24 h (P = 0.02). Of the six (26%) patients who died during hospital admission, five had raised TT/APTT at 24 h (P = 0.05). Two deaths were due to continued bleeding despite idarucizumab. Only 17% of patients received prohaemostatic treatments, and none received plasma derivatives. Despite assay availability, dabigatran drug level was only measured in eight patients.

Conclusion: Idarucizumab helped achieve haemostasis in 15 bleeding patients and allowed 6 patients to undergo urgent surgery. Half the patients had prolonged TT/APTT at 24 h post-idarucizumab, which was more likely to occur in patients with impaired renal function.
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http://dx.doi.org/10.1111/imj.13995DOI Listing
January 2019

HIT or miss? A comprehensive contemporary investigation of laboratory tests for heparin induced thrombocytopenia.

Pathology 2018 Jun 17;50(4):426-436. Epub 2018 Apr 17.

Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, Westmead, NSW, Australia; NSW Health Pathology, NSW, Australia; Sydney Centres for Thrombosis and Haemostasis, Westmead, NSW, Australia.

Heparin induced thrombocytopenia (HIT) is a rare but potentially fatal complication of heparin therapy, which in a proportion of patients causes platelet activation and thrombosis. Initial clinical assessment of the likelihood of HIT is facilitated by laboratory testing to confirm or exclude HIT. This prospective investigation was performed over an 18-month period, and has involved testing of over 300 test samples from over 100 consecutive patients. Clinical assessment by 4T score was supplemented by laboratory tests that comprised both immunological [lateral flow ('STiC'), chemiluminescence (AcuStar; HIT-IgG), ELISA (Asserachrom HPIA IgG)] and functional assays [SRA, platelet aggregation using whole blood ('Multiplate') and platelet rich plasma ('LTA')]. We observed both false positive and false negative test findings with most assays. Overall, the whole blood aggregation method provided a reasonable alternative to SRA for identifying functional HIT. STiC, AcuStar and ELISA procedures were fairly comparable in terms of screening for HIT, although STiC and AcuStar both yielded false negatives, albeit also resulting in fewer false positives than ELISA. The 4T score had less utility in our patient cohort than we were expecting, although there was an association with the likelihood of HIT. Nevertheless, we accept that our observations are based on limited test numbers. In conclusion, no single approach (clinical or laboratory) was associated with optimal sensitivity or specificity of HIT exclusion or identification, and thus, a combination of clinical evaluation and laboratory testing will best ensure the accuracy of diagnosis.
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http://dx.doi.org/10.1016/j.pathol.2017.11.089DOI Listing
June 2018

Thrombosis and Hemostasis in Surgery.

Semin Thromb Hemost 2017 10 29;43(7):649-652. Epub 2017 Sep 29.

Department of Haematology, Institute of Clinical Pathology and Medical Research, NSW Health Pathology, Westmead Hospital, Sydney, Australia.

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http://dx.doi.org/10.1055/s-0037-1605571DOI Listing
October 2017

Replacing warfarin therapy with the newer direct oral anticoagulants, or simply a growth in anticoagulation therapy? Implications for pathology testing.

Pathology 2017 Oct 19;49(6):639-643. Epub 2017 Aug 19.

Section of Clinical Biochemistry, University of Verona, Verona, Italy.

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http://dx.doi.org/10.1016/j.pathol.2017.04.011DOI Listing
October 2017

Flow Cytometry Protocols for Assessment of Platelet Function in Whole Blood.

Methods Mol Biol 2017 ;1646:369-389

ANZAC Research Institute, University of Sydney, Sydney, NSW, Australia.

Flow cytometry is a powerful tool for rapid evaluation of multiple functional properties of large numbers of platelets in whole blood. In the following chapter, we provide a number of flow cytometry-based protocols broadly aimed at (1) assessment of constitutively expressed platelet membrane receptors to diagnose inherited platelet bleeding disorders and (2) investigation of basal and agonist-induced platelet functional responses including generation of platelet-leukocyte aggregates, alpha and dense granule release, calcium flux, and phosphatidylserine exposure.
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http://dx.doi.org/10.1007/978-1-4939-7196-1_28DOI Listing
May 2018

Assessment of Platelet Function in Whole Blood by Flow Cytometry.

Authors:
Leonardo Pasalic

Methods Mol Biol 2017 ;1646:349-367

Deparments of Clinical and Laboratory Haematology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, NSW, 2145, Australia.

Evaluation of platelet function is important for understanding the physiology of hemostasis and thrombosis and is utilized in clinical practice to diagnose inherited and acquired platelet bleeding disorders. Flow cytometry is a powerful tool for rapid evaluation of multiple functional properties of large number of platelets in whole blood and offers many advantages over other traditional methods. Attention to pre-analytical factors is required to ensure biologically valid and robust results.
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http://dx.doi.org/10.1007/978-1-4939-7196-1_27DOI Listing
May 2018

Laboratory Testing Protocols for Heparin-Induced Thrombocytopenia (HIT) Testing.

Methods Mol Biol 2017 ;1646:227-243

Haematology Department, Sydney Centres for Thrombosis and Haemostasis, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, NSW Health Pathology, Westmead, 2145 NSW, Australia.

Heparin-induced thrombocytopenia (HIT) represents a significant high morbidity complication of heparin therapy. The clinicopathological diagnosis of HIT remains challenging for many reasons; thus, laboratory testing represents an important component of an accurate diagnosis. Although there are many assays available to assess HIT, these essentially fall into two categories-(a) immunological assays, and (b) functional assays. The current chapter presents protocols for several HIT assays, being those that are most commonly performed in laboratory practice and have the widest geographic distribution. These comprise a manual lateral flow-based system (STiC), a fully automated latex immunoturbidimetric assay, a fully automated chemiluminescent assay (CLIA), light transmission aggregation (LTA), and whole blood aggregation (Multiplate).
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http://dx.doi.org/10.1007/978-1-4939-7196-1_19DOI Listing
May 2018

Therapeutic monitoring of unfractionated heparin - trials and tribulations.

Expert Rev Hematol 2017 07;10(7):595-605

a Department of Haematology, Institute of Clinical Pathology and Medical Research, NSW Health Pathology , Westmead Hospital , Westmead , Australia.

Introduction: Heparin is one of the oldest biological medicines with an established role in prevention and treatment of arterial and venous thromboembolism. Published therapeutic ranges for unfractionated heparin (UFH) mostly precede the large increase in the number of activated partial thromboplastin time (APTT) reagent/instrument combinations that now show wide variability. Areas covered: This paper explores the use of UFH, the development of heparin therapeutic ranges (HTRs), and the strengths and limitations of the methods used to monitor heparin's anticoagulant effect. Expert commentary: Despite longstanding use of UFH for management of thromboembolic conditions, the optimal test for monitoring UFH remains undetermined. Although used extensively for monitoring UFH, routine APTT-derived HTRs are based on limited science that may have little relevance to current laboratory practice. Anti-FXa levels may provide better and more reliable HTRs; however, even these levels show considerable inter-laboratory variation, and there are insufficient clinical studies proving improved clinical efficacy. Alternative tests for monitoring UFH reported over time have not been proven effective nor feasible, secondary to technical or cost issues, or lack of general adoption. Thus, despite limited evidence of clinical utility, an uncomfortable marriage of convenience represented by heparin laboratory monitoring is unlikely to be terminated in the immediate future.
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http://dx.doi.org/10.1080/17474086.2017.1345306DOI Listing
July 2017

Novel (Oral) Anticoagulant Challenges in Surgery.

Semin Thromb Hemost 2017 Oct 8;43(7):706-715. Epub 2017 Jun 8.

Department of Laboratory Haematology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, NSW Health Pathology, Westmead, New South Wales, Australia.

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http://dx.doi.org/10.1055/s-0037-1602667DOI Listing
October 2017

Clinical and laboratory diagnosis of heparin induced thrombocytopenia: an update.

Pathology 2017 Jun 23;49(4):346-355. Epub 2017 Apr 23.

Department of Laboratory Haematology, Institute of Clinical Pathology and Medical Research and Westmead Hospital, NSW Health Pathology, Westmead, Australia; Sydney Centres for Thrombosis and Haemostasis, Australia.

Heparin remains a commonly used anticoagulant in prophylaxis and treatment of venous and arterial thrombosis, in addition to ensuring patency of artificial blood circuits such as cardiopulmonary bypass (CPB). Heparin induced thrombocytopenia (HIT) is a rare but potentially fatal complication of heparin therapy that results from production of polyclonal antibodies to heparin in complex, usually with platelet factor 4 (PF4). In a proportion of patients, this causes platelet activation and thrombin generation, which may result in thrombosis. However, identification of patients with HIT can be complicated as thrombocytopenia is common in hospitalised patients receiving heparin, and is usually due to other causes. Clinical assessment of the likelihood of HIT is paramount in order to make appropriate decisions regarding laboratory investigations and ongoing anticoagulation, especially given clinically expressed pro-thrombotic states. However, clinical assessment, on its own, cannot guarantee diagnosis or exclusion of HIT, and therefore is facilitated by laboratory testing, although unfortunately, this is frequently limited by local availability of assays and delay in availability of results. Nevertheless, there are an increasing number of available laboratory tests that can be used to identify antibodies causing HIT, including both immunological and functional assays. This narrative review will discuss the existing tools for clinical assessment in addition to evaluating the advantages and disadvantages of the available laboratory assays for HIT.
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http://dx.doi.org/10.1016/j.pathol.2017.02.005DOI Listing
June 2017

Laboratory Monitoring or Measurement of Direct Oral Anticoagulants (DOACs): Advantages, Limitations and Future Challenges.

Curr Drug Metab 2017 ;18(7):598-608

Pathology West, NSW Health Pathology. Australia.

Background: The Direct Oral Anticoagulants (DOACs) represent a new generation of antithrombotic agents, providing direct inhibition of either thrombin (factor IIa; FIIa) or activated factor X (FXa). Around the globe, their use is progressively rising, as these new agents replace the historical anticoagulants (heparin and vitamin K antagonists including warfarin) for various clinical conditions in medical practice. Other acronyms used to designate DOACs include TSOAC (target specific oral anticoagulants) and NOAC (novel; or non-vitamin K antagonist oral anticoagulants). Currently available DOACS include dabigatran (FIIa inhibitor), along with rivaroxaban, apixaban, edoxaban and betrixaban (FXa inhibitors).

Objective: This narrative review aims to briefly summarise the evidence concerning utility of different laboratory assays for qualitative or quantitative assessment of DOACs, emphasizing the difference between 'drug monitoring' and 'drug measurement' and ultimately discussing advantages and limitations of these processes.

Results And Conclusion: Recently, the dogma that these innovative anticoagulant agents will not necessitate laboratory testing has been challenged with the recognition that assessment of drug concentration or activity may be required in some circumstances, although this does not immediately translate to the concept of 'drug monitoring'.
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http://dx.doi.org/10.2174/1389200218666170417124035DOI Listing
September 2018

Borrowing (once again) from the animal kingdom.

Blood Transfus 2017 07 25;15(4):294-295. Epub 2016 Jul 25.

Department of Haematology, Sydney Centres for Thrombosis and Haemostasis, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology NSW, Westmead Hospital, NSW, Australia.

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http://dx.doi.org/10.2450/2016.0104-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490723PMC
July 2017