The effect of the direct oral anticoagulants (DOACs) on haemostasis tests. Emmanuel J Favaloro, Haematology, ICPMR, Pathology West, Sydney Centres for Thrombosis and Haemostasis, Westmead Hospital (with assistance from plethora of others including the RCPA Haematology QAP) emmanuel.favaloro@health.nsw.gov.au February, 2016
Background publications available from speaker: Favaloro EJ, Lippi G, Koutts J. Laboratory testing of anticoagulants - the present and the future. Pathology, 2011; 43(7): 682 692. Favaloro EJ, Lippi G. Editorial. Laboratory testing and/or monitoring of the new oral anticoagulants/antithrombotics: For and against? Clin Chem Lab Med. 2011;49(5):755-7 Favaloro EJ, Lippi G. The new oral anticoagulants and the future of haemostasis laboratory testing. Biochemia Medica (Zagreb), 2012;22(3):329-41 Favaloro EJ, Bonar R, Butler J, Marsden K. Laboratory testing for the new oral anticoagulants: A review of current practice. Pathology. 2013 Jun;45(4):435-7 Lippi G, Favaloro EJ. Urgent monitoring of dabigatran plasma levels. Less is sometimes more. Polish Archives of Internal Medicine (Pol Arch Med Wewn). 2014 Nov 28;124(11):639-40 Lippi G, Favaloro EJ. Recent guidelines and recommendations for laboratory assessment of the direct oral anticoagulants (DOACs): is there consensus? Clin Chem Lab Med, 2015 Feb 1;53(2):185-97 Lippi G, Favaloro EJ. Laboratory monitoring of warfarin in the era of direct oral anticoagulants. Lancet Haematol. 2015 Jun;2(6):e223-4. Favaloro EJ. Anticoagulant therapy: present and future. Semin Thromb Hemost. 2015 Mar;41(2):109-12 Bonar R, Favaloro EJ, Mohammed S, Pasalic L, Sioufi J, Marsden K. The effect of dabigatran on haemostasis tests: a comprehensive assessment using in-vitro and ex-vivo samples. Pathology, 2015. 47(4):355-64. Favaloro EJ, Lippi G. Laboratory testing in the era of direct or non-vitamin k antagonist oral anticoagulants: a practical guide to measuring their activity and avoiding diagnostic errors. Semin Thromb Hemost. 2015 Mar;41(2):208-27. Bonar R, Favaloro EJ, Mohammed S, Ahuja M, Pasalic L, Sioufi J, Marsden K. The effect of the direct factor Xa inhibitors apixaban and rivaroxaban on haemostasis tests: a comprehensive assessment using in vitro and ex vivo samples. Pathology, 2016 Jan;48(1):60-71. Favaloro EJ, Lippi G. Interference of direct oral anticoagulants (DOACs) in hemostasis assays: High potential for diagnostic false positives and false negatives. Blood Transfusion, 2017; DOI 10.2450/2016.0301-16 Lippi G, Favaloro EJ. Laboratory monitoring of direct oral anticoagulants (DOACs). The perfect storm? Annals of Translational Medicine; 2017, Jan;5(1):6. 2
Direct oral anticoagulants (DOACs) Main agents: Dabigatran (etexilate; Pradaxa; Boehringer Ingelheim Pty Ltd): Direct thrombin inhibitor Rivaroxaban (Xarelto; Bayer Ltd): Direct Factor Xa inhibitor Apixaban (Eliquis; Bristol-Myers Squibb Pharmaceuticals): Direct Factor Xa inhibitor (Edoxaban (Savaysa, Daiichi Sankyo): Direct Factor Xa inhibitor; Others coming) 3
Direct oral anticoagulants Terminology/acronyms: New or novel oral anticoagulants (NOACs) Eventually not so new or novel, so direct oral anticoagulants coined (DOACs) Push for return/continuation of NOACs (nonvitamin K antagonist oral anticoagulants). Not-so-new oral anticoagulants (NOACs) Others TSOCs (target specific), DOACs recently endorsed by ISTH (by one vote!) 4
Direct oral anticoagulants General indications summarised adults (dabigatran, apixaban, rivaroxaban): Prevention of venous thromboembolic events (VTE) (major orthopaedic surgery of the lower limb) Prevention of stroke and systemic embolism in nonvalvular atrial fibrillation (and at least one additional risk factor for stroke). Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE) Prevention of recurrent DVT and PE 5
DOAC usage an increasing trend: ABC news report: <http://www.abc.net.au/news/2017-02-12/prescriptions-for-new-blood-thinning-drugs-skyrocket/8250856> Last accessed 2017-02-14 Pharmaceutical Benefits Scheme (PBS) Australian Statistics on Medicines. Available at: <http://medicarestatistics.humanservices.gov.au/statistics/pbs_item.jsp>; and <http://www.pbs.gov.au/info/browse/statistics#asm> Last accessed 2017-02-15 6
Laboratory testing a changing landscape Item 65120: Prothrombin time (including INR where appropriate), activated partial thromboplastin time, thrombin time (including test for the presence of heparin), test for factor XIII deficiency (qualitative), Echis test, Stypven test, reptilase time, fibrinogen, or 1 of fibrinogen degradation products, fibrin monomer or D-dimer Medicare test data. Available at: <http://medicarestatistics.humanservices.gov.au/statistics/mbs_item.jsp>; Last accessed 2017-02-15 7
Laboratory testing a changing landscape 8
Direct oral anticoagulants Contact (Intrinsic) pathway Contact activation Tissue Factor (Extrinsic) pathway Vascular injury-trauma FXII FXIIa FXI FXIa FIX FIXa FVIIa FVII rivaroxaban apixaban FX Prothrombin FVIIIa FXa x FVa Thrombin x FX dabigatran Fibrinogen Fibrin 9
dabigatran - the basics Summary Affects TT > APTT > PT Affects drvvt > APTT Some reagent variability 10
rivaroxaban - the basics Summary Affects PT > APTT Affects drvvt ~ = PT Some reagent variability 11
apixaban - the basics Summary Hardly affects PT, APTT Does affects drvvt Some reagent variability 12
DOACs The basics - summary Dabigatran can be accurately measured using dtt/dti methods (commercial and in house) Apixaban & rivaroxaban can be accurately measured using anti-xa methods (using specific drug as calibrator) Low level sensitivity issues (20-25ng/mL for all assays) High level sensitivity issues (dilute samples for accurate reading) For routine PT & APTT assays: Dabigatran APTT > PT Rivaroxaban PT > APTT Apixaban neither unless sensitive reagent Generally, drvvt more sensitive than either PT or APTT 13
DOACs a summary of additional findings (data not shown) Although dabigatran can be accurately measured using dtt/dti methods, apixaban & rivaroxaban do not affect dtt/dti assays Although apixaban & rivaroxaban can be accurately measured using anti-xa methods, dabigatran does not affect anti-xa assays Some other tests not affected by DOACs: Fibrinogen (except for some assays (IL Fib C) for higher levels of dabigatran) Protein S antigen levels (free Protein S) Protein C by chromogenic assay Many other tests affected by DOACs: Include factor assays, Protein S clot based assays, APCR assays, lupus anticoagulants, antithrombin (selective) 14
DOACs Antithrombin Dabigatran affects antithrombin assays using an anti-iia method, but not an anti-xa method Apixaban & rivaroxaban affect antithrombin assays using an anti-xa method, but not an anti-iia method 15
DOACs factors All factor assays potentially affected May occur if clinician wants factor assays for unexpectedly raised APTT and/or PT 16
Ratio Ratio Ratio DOACs LA All DOACs affect LA Raises both drvvt screen and confirm, as well as (potentially) SCT/APTT, etc Potential false positive LA with dabigatran & rivaroxaban Potential false negative LA 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 DOAC-D-1 10 36 86 190 385 744 10 36 86 190 385 744 10 36 86 190 385 744 DOAC-D-5 Screen Confirm Ratio DOAC-D-3 DOAC-D-6 DOAC-D-4 DOAC-D-2 DOAC-D-1 DOAC-D-5 DOAC-D-3 DOAC-D-6 DOAC-D-4 DOAC-D-2 Dabigatran survey samples DOAC-D-1 DOAC-D-5 DOAC-D-3 DOAC-D-6 DOAC-D-4 DOAC-D-2 5.0 5.0 4.5 Screen Confirm Ratio 4.5 Screen Confirm Ratio 4.0 4.0 3.5 3.5 3.0 3.0 2.5 2.0 1.5 1.0 0.5 0.0 7 16 25 44 87 211 417 638 7 16 25 44 87 211 417 638 7 16 25 44 87 211 417 638 RIV14-8 RIV14-7 RIV14-2 RIV14-5 RIV14-4 RIV14-3 RIV14-6 RIV14-1 RIV14-8 RIV14-7 RIV14-2 RIV14-5 RIV14-4 RIV14-3 RIV14-6 RIV14-1 Rivaroxaban survey samples RIV14-8 RIV14-7 RIV14-2 RIV14-5 RIV14-4 RIV14-3 RIV14-6 RIV14-1 17 2.5 2.0 1.5 1.0 0.5 0.0 8 12 20 33 60 118 296 501 8 12 20 33 60 118 296 501 8 12 20 33 60 118 296 501 APIX14-3 APIX14-7 APIX14-6 APIX14-5 APIX14-4 APIX14-8 APIX14-2 APIX14-1 APIX14-3 APIX14-7 APIX14-6 APIX14-5 APIX14-4 APIX14-8 APIX14-2 APIX14-1 APIX14-3 APIX14-7 APIX14-6 APIX14-5 APIX14-4 APIX14-8 APIX14-2 APIX14-1 Apixaban survey samples
DOACs Factor inhibitors All DOACs affect factor assays Behave like inhibitors Potential false positive factor inhibitor 14-03b outlier - reported 0.5BU/mL FVIII inhibitor = detected. Pool of normal plasma; no inhibitor present; = false positive (n=1/51 = <2% error rate ) 14-03a - dabigatran (~800ng/mL) sample; = false positive (n=49/51 = >97% error rate ) 18
DOACs Factor inhibitors and beyond INH15-03a = normal pooled plasma spiked with rivaroxaban (~638ng/mL) All method median result = 0.5 BU Range of reported 'inhibitor' levels undetectable to 3 BU Interpretations = inhibitor detected (46%) vs not detected (54%) 19
DOACs RCPA QAP Module G 3 years worth of dabigatran surveys Very reproducible findings with dtt/dti assays High concordance of medians of samples repeat tested in separate surveys Moderate CVs; very few outliers;?revise ALP Interesting mix of LL/ML/HL with detected 2 years worth of apixaban & rivaroxaban surveys Very reproducible findings with anti-xa assays Moderate CVs; very few outliers;?revise ALP High concordance of medians for rivaroxaban samples repeat tested in separate surveys Have not been able as yet to assess concordance from medians of apixaban samples repeat tested in separate surveys Interesting mix of LL/ML/HL with detected Any problems or concerns? Contact the RCPA QAP! 20
Simple clinical view of hemostasis Activation of platelets / coagulation factors Simple clinical view of thrombosis Over activation of platelets / coagulation factors Lots of exciting biochemistry Too much exciting biochemistry CLOT Thrombosis 21
Simple clinical view of anti-coagulant / anti-platelet therapy & monitoring: Activation of platelets /coagulation factors Drugs exciting biochemistry is inhibited Thrombosis is inhibited (easy for lab to measure decreased CLOT formation or platelet activity ) 22
DOACs Summary Level Level Lippi & Favaloro. Recent guidelines and recommendations for laboratory assessment of the direct oral anticoagulants (DOACs): is there consensus? Clin Chem Lab Med, 2015 Feb 1;53(2):185-97 Do not undertake testing for: Factors LA Thrombophilia tests inhibitor assays 23
Testing DOACs at Westmead - summary Coagulation test Anti-Xa DOACs (Rivaroxaban) Anti-Xa DOACs (Apixaban) Effect of Anti-IIa DOACs (Dabigatran) VKAs UH LMWH PT/INR ++ (+) + ++ -/+ - aptt + (+) ++ + ++ -/+ TT - - ++ - ++ +/- Anti-Xa ++ ++ - - ++ ++ drvvt ++ ++ ++ ++ -/++ - Lippi & Favaloro. Recent guidelines and recommendations for laboratory assessment of the direct oral anticoagulants (DOACs): is there consensus? Clin Chem Lab Med, 2015 Feb 1;53(2):185-97 Factor assays ++ ++ ++ ++/- ++/- -/+ LA ++ ++ ++ ++ -/++ - PC, PS, AT -/+ -/+ -/+ -/+ -/+ -/+ Inhib. assays ++ ++ ++ -/+ -/+ -/+ 24
Acknowledgments Meeting organisers RCPAQAP Haematology, especially Roslyn Bonar Diagnostic Haemostasis laboratory staff Soma Mohammed Jane McDonald Ella Grezchnik Monica Ahuja Shabana Azimulla Yifang Zhang Haemostasis = Love Everybody talks about it, nobody understands it. 25