Annual meeting of the Royal Belgian Society of Laboratory Medicine New anticoagulants: influence on routine coagulation testing and how to detect an overdose Prof. François Mullier Université catholique de Louvain, CHU UCL Namur Associate head of laboratory of clinical biology

No relevant conflicts of interest to declare Scientific Advisory Board Research Support/P.I. No relevant conflicts of interest to declare Employee Consultant Major Stockholder Speakers Bureau Honoraria Speaker fees for Boehringer Ingelheim, Bayer Healthcare and Bristol-Myers Squibb-Pfizer Scientific Advisory Board 2

Take home message 2 key opinion leaders says: Registration by regulatory agencies and their widespread implementation in clinical laboratories are “urgently” needed Dabigatran versus warfarin in patients with atrial fibrillation. Connolly SJ, Ezekowitz MD, Yusuf S, Eikelboom J, Oldgren J, Parekh A, Pogue J, Reilly PA, Themeles E, Varrone J, Wang S, Alings M, Xavier D, Zhu J, Diaz R, Lewis BS, Darius H, Diener HC, Joyner CD, Wallentin L; RE-LY Steering Committee and Investigators. N Engl J Med. 2009 Sep 17;361(12):1139-51. Idarucizumab for Dabigatran Reversal. Pollack CV Jr, Reilly PA, Eikelboom J, Glund S, Verhamme P, Bernstein RA, Dubiel R, Huisman MV, Hylek EM, Kamphuisen PW, Kreuzer J, Levy JH, Sellke FW, Stangier J, Steiner T, Wang B, Kam CW, Weitz JI. N Engl J Med. 2015 Aug 6;373(6):511-20. 3

Outline Introduction Why to measure DOACs? When to measure DOACs? - Measurement in the perioperative setting - Measurement in urgent situations How to measure DOACs?: International, national and regulatory recommendations Influence of DOACs on other coagulation testing Conclusions

PK and PD rivaroxaban apixaban edoxaban dabigatran 5

PK and PD dabigatran etexilate (PRADAXA®) rivaroxaban (XARELTO®) apixaban (ELIQUIS®) edoxaban (LIXIANA®) Target Thrombin Factor Xa Bioavailability (%) 3-7% Not affected by food 80 to 100% for the 10 mg 66% for the 15 and 20 mg (fasted)* 50% 62% Prodrug Yes – activated by esterase (CES1) No Half-life (hours) 11-13 5-13 8-15 10-14 TMAX (hours) 0.5-2.0 2.0-4.0 3.0-4.0 1.0-2.0 Renal clearance 80% 33% 25% Metabolism P-gp CYP3A4 CYP3A4/5, 1A2, 2J2 CYP3A4/5 * these dose regimen have to be taken with food. 6

Indications 7

Some figures in Belgium Already 107582 patients on DOACs in 2014 Pharmanet, INAMI 8

Why to measure DOACs? 9

Why to measure DOACs? Cons: PK-PD studies: preditable response All RCT were performed without monitoring Large therapeutic range Freyburger et al., 2011; Mani et al., 2013; Samama et al., 2013 10

Why to measure DOACs? Pros: Correlation between clinical events and plasmatic dabigatran/edoxaban concentrations Possible improvement of the B/R balance Reilly PA et al., JACC 2013; Douxfils et al., Exp. Op. Drug Saf. 2015.`; Ruff et al. The Lancet 2015. 11

Why to measure DOACs? Interindividual variability (EMA SmPC 2013; Ten Cate, H. Thromb Haemost 2012; Ten Cate, H. Thromb J 2013; Reilly PA et al. JACC 2013; Chan et al. JTH 2015; Douxfils et al. JTH 2015; Douxfils et al. Exp. Op. Drug. Saf. 2015) Mean (min-max) concentrations Dabigatran 110mg (n=90) Rivaroxaban 20 mg (n=37) Apixaban 5 mg (n=73) Trough Peak Trough Peak Trough Peak Testa S, Thromb Res 2016 High inter-individual variability Variables: age, weight, renal function, CYP3A4 and P-gp modulators Gong IY, Can J Cardiol 2013

Why to measure DOACs in the perioperative setting? VKA: discontinuation few days before surgery or invasive procedures laboratory testing just before the procedure: INR should be lower than 1.5 (ACCP 2012) DOACs: Quick onset of action, relative short half-live discontinuation of DOACs a few days before surgery or invasive procedures would be sufficient to allow clearance of these drugs from the circulation  Is the laboratory measurement of residual drug levels needed? Tripodi J Thromb Haemost 2016 Spyropoulos et al J Thromb Haemost 2016. Douketis J et al. Chest 2012 13

Why to measure DOACs in the perioperative setting? Cons (against the laboratory strategy, in favor of the pharmacokinetic strategy): Simpler: bleeding risk of the procedure, renal function,age, weight, other medications, dose of the DOAC, timing of the last DOAC administration No precise guidance about which tests should be used The specific assays are not readily available and require expertise The specific assays are expensive There are no reliable cut-off values for drug concentrations to make decisions on whether surgery or invasive procedures could be safely carried out. Some procedures could be unnecessarily postponed based on borderline laboratory results that are difficult to interpret Tripodi J Thromb Haemost 2016 Spyropoulos et al J Thromb Haemost 2016. 14

Why to measure DOACs in the perioperative setting? Cons (against the laboratory strategy, in favor of the pharmacokinetic strategy): RELY,ROCKET-AF, ARISTOTLE : the pharmacokinetic strategy was adopted with no excess bleeding in comparison to warfarin Feeling of some clinicians that the laboratory issue may undermine the implementation of DOAC Tripodi J Thromb Haemost 2016 Spyropoulos et al J Thromb Haemost 2016. 15

Why to measure DOACs in the perioperative setting? Pros (in favor of the laboratory strategy, against the pharmacokinetic strategy): Pharmacokinetic strategy is not so simple: recommendations based on renal function are not consistent with a risk of confusion and mismanagement Pharmacokinetic strategy is not so simple: categorization into low bleeding risk or high bleeding risk is also not consistent CrCl should be measured as close as possible to the performance of the procedure (as it may considerably over time) The reliability of the dose and timing of the last DOAC administration are based on the assumption that the patient correctly reports the true dose of the drug, the exact timing of administration and the type of other concomitant drugs Influence of genetic variation on the DOAC response is not well known,  clearence is not always what it is anticipated. PK: surrogate information, Labo: direct information Tripodi J Thromb Haemost 2016 Spyropoulos et al J Thromb Haemost 2016. 16

Why to measure DOACs in the perioperative setting? Pros (in favor of the laboratory strategy, against the pharmacokinetic strategy): Laboratory strategy would presumably have a much stronger impact in the case of medical-legal issues There are systematic reviews/guidance/guidelines (ISTH, British Society of Hematology) about which tests should be used Specific assays are available from many commercial diagnostic companies and can be set up on regular coagulometers, where they can be run at any time without special expertise The specific assays are not so expensive (15-20 EUR, > INR) and are limited to specific situations  no impact on the healthcare system (cost of DOAC < VKA) Cut-offs?: clinical trials are still needed to establish these cut-offs with certainty but cut-offs are available from EMA, ISTH and GIHP (between 30 and 50ng/ml) Tripodi J Thromb Haemost 2016 Spyropoulos et al J Thromb Haemost 2016. 17

Why to measure DOACs in the perioperative setting? Pros (in favor of the laboratory strategy, against the pharmacokinetic strategy): Situations where laboratory data are difficult to interpret exist but solution should be based on common sense Douketis et al. J Thromb Haemost 2016 Effect of standardized perioperative dabigatran interruption on residual anticoagulation effect at the time of surgery or procedure: 20% of patients had ‘abnormal’ test values at the time of the surgery/procedure is a cause of concern and should be seen as an indication to consider the laboratory strategy. RELY,ROCKET-AF, ARISTOTLE : clinical trials are not entirely representative of the real life (strict control, many exclusion criteria,..) Lab testing (if properly used) may help clinicians to better manage patients and would favor the implementation of DOACs Tripodi J Thromb Haemost 2016 Spyropoulos et al J Thromb Haemost 2016. 18

Clinical trials on perioperative DOAC management with laboratory data Schulman et al. 2015: first prospective study of periop management of patients on dabigatran etexilate without bridging: 48 hours may be not enough before high bleeding risk surgery Godier et al. 2015 - CORIDA study (COncentrations of Rivaroxaban and Dabigatran): 48 hours not enough before high bleeding risk surgery CORIDA 2: results in submission PAUSE trial (Perioperative Anticoagulant Use for Surgery Evaluation Study (PAUSE) awaiting results for 2017 Schulman et al. Circulation 2015 Godier et al. Thromb Res 2015

When do we need to measure DOACs in urgent situations? Bleeding or recurrence of thrombosis (to assessing the potential contribution of DOACs) Before an invasive procedure (elective or urgent surgery at risk of bleeding, thrombolysis) to make decision about timing of these procedures or to determine whether patients with acute ischemic stroke can safely be given fibrinolytic therapy. To select patients who will benefit from antidote administration (RE-VERSE AD study; at baseline, 25 patients had a normal aPTT  more sensitive tests than the aPTT are needed to best identify patients who will benefit from idarucizumab and to monitor their response to treatment). To monitor the extent of reversal achieved when reversal agents are given Douxfils et al. Exp. Op. Drug. Saf. 2015. Weitz J, Eikelboom J. Circulation 2016 20 20

Assays sensitive to low plasma concentrations of dabigatran are required to assess the reversal by idarucizumab RE-VERSE AD interim results: primary endpoint by dTT reversal Assay upper limit of normal Idarucizumab 2x 2.5 g dTT (s) 130 110 70 60 50 40 30 20 120 100 90 80 1h 2h 4h 12h 24h Baseline Between vials 10–30 min Time post idarucizumab Uncontrolled bleeding Emergency surgery or procedure Idarucizumab 2x 2.5 g dTT (s) 130 110 70 60 50 40 30 20 120 100 90 80 1h 2h 4h 12h 24h Baseline Between vials 10–30 min Time post idarucizumab Interim analysis includes data for the first 90 patients. Pollack CV et al. N Engl J Med 2015:373:511–20

Idarucizumab for dabigatran reversal- Does one dose fit all? The 5 g idarucizumab decreased dabigatran concentration from 3000ng/ml to 500 ng/mL. However, the dabigatran concentration returned to 1126 ng/mL at 7 h after idarucizumab administration, = rebound of drug levels This case highlights the need for continued monitoring of dabigatran concentrations and coagulation parameters following idarucizumab administration. Rottenstreich A et al. Thromb Res 2016 Miller L et al. J Emerg Med 2016

When do we need to measure DOACs in urgent situations? For andexanet administration: The dose is determined by which oral FXa inhibitor the patient is taking and the time from the last dose This can lead to unnecessary administration or underdosing if the clinical information is incorrect Ready access to rapidly available, calibrated tests is needed to ensure reversal agents are given appropriately The cost of andexanet is estimated to be between 3000 and 4000 EUR per dose. Therefore, ready access to rapidly available, calibrated tests is needed to ensure that reversal agents are given appropriately. Weitz J, Eikelboom J. Circulation 2016 23 23

Guidance of the SSC of the ISTH (2/2) For the administration of reversal agents: In patients with serious bleeding, a drug concentration, > 50 ng/mL is likely sufficiently high to warrant antidote administration whereas in those requiring an urgent intervention associated with a high risk of bleeding, antidote administration should be considered if the drug concentration exceeds 30 ng/mL Note: This algorithm needs to be validated prospectively Levy et al. J Thromb Hemost 2016

When it may be useful to measure DOACs in non urgent situations? In patients with potential drug interactions that affect the pharmacokinetics of DOACs (P-gp) In patients with extreme body weight (< 50 or > 110 kg) In elderly patients (> 75 years of age) with renal failure In case of accumulating interfering factors Douxfils et al. Exp. Op. Drug. Saf. 2015. Weitz J, Eikelboom J. Circulation 2016 Martin et al. J Thromb Haemost 2016 25 25

How to interpret DOAC assays? dabigatran etexilate (PRADAXA®) rivaroxaban (XARELTO®) apixaban (ELIQUIS®) edoxaban (LIXIANA®) TMAX (hours) 0.5-2.0 2.0-4.0 3.0-4.0 1.0-2.0 TTROUGH (hours) 12.0 24.0 26

How to interpret DOACs assays in urgent situations? Use the appropriate assay! Limit of quantification, linearity and Interferences! Safety threshold for surgery with high risk of bleeding Drug reversal in case of serious bleeding Risk of bleeding Ischemic stroke: no consensus, IV thrombolysis in patients with 50 to 100 ng/mL < 30 ng/mL > 50 ng/mL Trough measurement 200ng/ml Levy JH, J Thromb Haemost 2016 Baglin T, J Thromb Haemost 2013 Pernod G, Arch Cardiovasc Dis 2013 Seiffge DJ, Circulation 2015 27 27

How to interpret DOACs assays in non urgent situations? More complex! Absence of therapeutic range (concentrations associated with bleeding or thrombosis Expected plasma concentration or on-therapy range (5th percentile trough concentration - 95th percentile peak concentration) Study population: atrial fibrillation Through conc. (ng/mL) 5th-95th Peak On-therapy range (ng/mL) Dabigatran 150 mg twice daily 64-443 31-225 31-443 Rivaroxaban 20 mg daily 6 - 87 189 - 419 6 - 419 Apixaban 5 mg twice daily 41 - 230 91 - 321 41 - 321 Edoxaban 60 mg daily 10 - 40 120 - 250 10 - 250 28 Kitchen S, et al. Br J Haematol. 2014; Cuker A, J Thromb Thrombolysis 2016; Samuelson BT Chest 2016 28

How to measure DOACs? Requirements Readily available 24h/day and 7 days/week Easily performed short turnaround time Reliable for measurement of “low” and “high “ concentrations < 30 to > 500ng/mL Since measurement of the conc is most of the time require in emergency situation, the assay must be readily available and have a short…. Gold standard: liquid chromatography with tandem mass spectrometry (LC-MS/MS) Baglin T, J Thromb Haemost 2014 Dale BJ, Br J Haematol 2015 Cuker A, J Thromb Thrombolysis 2016 29

Turn around time 38 consecutive patients with acute ischemic or hemorrhagic stroke under Rivaroxaban (last intake <48 h) in which RivLev determined by Biophen assay TAT:34 min (IQR 29–65 min). similar for on-hours and off-hours-TATs as well as for early and late patient arrival Feasible for use in emergency treatment Further research to evaluate the role of rivaroxaban concentration to guide acute treatment decisions is warranted. Seiffge DJ, et al. J Thromb Thrombolysis 2016

How to measure DOACs: summary of systematic reviews and recommendations Focaliser sur dabigatran avec un cadre? Cuker A., et al. J Am Coll Cardiol. 2014 Lippi G. Clin Chem Lab Med. 2015 Samuelson BT, Cuker A. Blood Rev 2016

Mass spectrometry : advantages and limitations of the gold standard method specificity labour-intensive preparation sensitivity LOD around 1 ng/mL LOQ around 3 ng/mL complexity of the technique selectivity compared to coagulation-based assay cost >< availability reproducibility intra-assay precision < 6% inter-assay precision < 10% Lack of standardization: in-house validation matrix effect interference with plasma phospholipids presence of other compounds removal of proteins interference by drug metabolites (either active or not) accuracy external quality control turn-around time Douxfils J., et al. Trends in Analytical Chemistry. 2016

Standard laboratory assays (PT/APTT) for DOACs Poor comparability of APTT/PT with specific assays 33 Testa S. et al, J Thromb Haemost 2016

Dabigatran: aPTT APTT is not reliable: not sensitive enough to dabigatran not possible to estimate dabigatran concentration normal aPTT cannot exclude the presence of dabigatran multiple other biological variable interfering with aPTT Do not calibrate with commercial standards Douxfils J,, Mullier F et al. Thromb Haemost. 2012 Douxfils J,, et al. Thromb Haemost. 2013 Hawes E. M., et al. JTH. 2013 Baglin T., et al. JTH. 2013 Van Blerk M., et al. Thromb Haemost. 2015 Samuelson BT, et al. Chest 2016

TT may be useful for low concentrations Often used in clinical practice even if it is not recommended Normal TT excludes clinical relevant dabigatran level A prolonged TT is not always associated with a concentration higher than 30 ng/ml  some anesthesiologists/surgeons may uselessly delay an invasive procedure Lack of standardisation and specificity (heparin bridging, inflammatory syndrome, fibrin degradation products…) Several biological and analytical variables: Thrombin origin Concentration of thrombin Lot to lot reagent differences Instrumentation/Storage Lessire S, Douxfils J et al. Thromb Res 2015; Douxfils J, Lessire S et al. Thromb Haemost. 2015; Chin et al. Br J Clin Pharmacol 2014. 35

Dabigatran: Dilute Thrombin Time and Ecarin Chromogenic Assay Hemoclot® Thrombin Inhibitors (HTI) and Ecarin Chromogenic assay (ECA) and STA®-ECA II (ECA II) useful for normal and high dabigatran concentrations but lower limits of quantitation between 30 and 50 ng/mL. Stangier J and coll. Blood Coagul Fibrin 2012 Lange U and coll. Pathophysiology of Haemostasis and Thrombosis 2003 Gosselin RC and coll. Ann Pharmacother 2013 Douxfils J and coll. Thromb Haemost 2013 Hawes EM and coll. J Thromb Haemost 2013 Antovic JP and coll. Eur J Clin Pharmacol 2013 Douxfils J, Mullier F and coll. Thromb Haemost 2012 van Ryn J and coll. Thromb Haemost 2010 Skeppholm M. and coll. Thromb Res 2014

Dabigatran and dedicated coagulation assays : External UKNEQAS survey

Dabigatran and dedicated coagulation assays : External UKNEQAS survey High CVs were observed for the two samples with lower levels of dabigatran. Between center agreement was better for sample S14:13 (median concentration 158.5ng/ml, CV 19.1%).

Dabigatran and dedicated coagulation assays : External UKNEQAS survey Only 3 CE marked assays Most of the assays are useful for normal and high concentrations but have lower limits of quantitation between 30 and 50 ng/mL Stangier J et al. Blood Coagul Fibrin 2012; Lange U et al. Pathophysiology of Haemostasis and Thrombosis 2003; Gosselin RC et al. Ann Pharmacother 2013; Douxfils J et al. Thromb Haemost 2013, Hawes EM et al. J Thromb Haemost 2013; Antovic JP et al. Eur J Clin Pharmacol 2013; Douxfils J, Mullier F et al. Thromb Haemost 2012; van Ryn J et al. Thromb Haemost 2010; Skeppholm M. et al. Thromb Res 2014

Dabigatran and dedicated coagulation assays : Other international surveys UKNEQAS 2015 Sample 15:01(n=56) : median 92ng/ml: overall CV: 15.1% Sample 15:02 (n=55): median 154 ng/ml, overall CV: 16.7% ECAT 2015 Sample 15:88 (n=111): median 131 ng/ml, overall CV: 15.4% Sample 15:89 (n=112): median 235 ng/ml, overall CV: 11.6%

New specific tests are available for low dabigatran concentrations Good accuracy in the low concentration range HemosIL Direct Thrombin Inhibitor also accurate (UKNEQAS 2014) Douxfils J,, et al. Thromb Haemost. 2015.

Comparison of specific assays for dabigatran Importance to use specific assays to make decisions in the perioperative management of patients Lessire et al. Submitted - Blood coagulation & fibrinolysis

Assays sensitive to low plasma concentrations of dabigatran are required to assess the reversal by idarucizumab RE-VERSE AD interim results: primary endpoint by dTT reversal Assay upper limit of normal Idarucizumab 2x 2.5 g dTT (s) 130 110 70 60 50 40 30 20 120 100 90 80 1h 2h 4h 12h 24h Baseline Between vials 10–30 min Time post idarucizumab Uncontrolled bleeding Emergency surgery or procedure Idarucizumab 2x 2.5 g dTT (s) 130 110 70 60 50 40 30 20 120 100 90 80 1h 2h 4h 12h 24h Baseline Between vials 10–30 min Time post idarucizumab Interim analysis includes data for the first 90 patients. Pollack CV et al. N Engl J Med 2015:373:511–20 Lower limit of quantitation: 30-50ng/ml!

Heparin-calibrated chromogenic anti-Xa assays Correlation only between low anti-Xa inhibitors conc. and heparin anti-Xa activity High inter-assay variability: no relationship between anti-Xa inhibitor concentration and heparin anti-Xa U/mL Given the availability of heparin calibrated anti-xa assays, the performance of these assays to mesure direct anti-Xa inhibitors have been tested. Direct anti-Xa inhibitors yield high heparin anti-Xa activity Correlation between drug conc. and heparin anti-Xa U/mL only over calibration ranges: low drug concentrations Variabiliy between commercial kits and calibrators: no relationship between drug conc. and heparin anti-Xa U/mL Suitable for ruling out presence of direct anti-Xa Should not be used to quantify direct anti-Xa Gosselin R, Ann Pharmacother 2015 Gosselin R, J Thromb Haemost 2016 Samama MM, Thromb Haemost 2010 44

Specific tests for direct anti-Xa concentration measurement: chromogenic anti-Xa assays Advantages Drawbacks Same reagents for measurement of UFH, LMWH anti-Xa activity and direct anti-Xa inhibitors Ready-to-use reagents Not affected by pre-analytical variables and alterations of clotting factor levels Measurement in plasma/serum High correlation with LCMSMS Specific calibrators and controls for each anti-Xa inhibitor: Rivaroxaban: available Apixaban: available Edoxaban: coming soon Lack of standardization: a reference international calibrator is required Each laboratory should establish, riva, api and edoxaban-specific standard curves Harenberg J, Clin Chem Lab Med 2016 Cuker A, J Thromb Thrombolysis 2016 Douxfils J, Bio Med Res Int 2015 Dale BJ, Br J Haematol 2015 Gosselin RC, Arch Pathol Lab Med 2014 Cuker A, JACC 2014 45

Intra-assay CV %: < 5% Inter-assay CV%: < 10% Specific chromogenic anti-Xa assays for rivaroxaban and apixaban measurement Reagents: one- or two-stage assay, different buffers, dilution factors, concentrations of Xa, types of chromogenic substrate Methods with exogenous antithrombin: over estimation of rivaroxaban Mani H, Thromb Haemost 2012 ; Helin TA, Clin Chem 2013 ; Asmis IM, Thromb Res 2012, Gosselin R Arch Pathol Lab Med 2014 Calibrators: 4 to 5 levels from 0 to 500 ng/mL (Stago, Hyphen, Technoclone) Lower limit of detection/quantification: ~ 20-30 ng/mL (sometimes lower Mani H, Thromb Haemost 2012 , Lessire S. CATH 2016 Accepted) Upper limit of quantification: ~ 400-600 ng/mL (if higher: dilution in buffer/plasma) Chromogenic anti-Xa assays are available from many commercial diagnostic companies. They differ in the type of methods, Biophen DiXa: specific for direct anti-Xa; Insensitive to the presence of heparin-like anti-Xa Berichrom contains AT Intra-assay CV %: < 5% Inter-assay CV%: < 10% Samama MM, Thromb Haemost 2010 ; Becker RC, J thromb Thrombolysis 2011 ; Douxfils J, Thromb Res 2012 ; Mani H, Thromb Haemost 2012 Douxfils J, Thromb Haemost 2013 ; Barrett YC, Thromb Haemost 2013 ; Francard S, Thromb Haemost 2014 Package inserts from diagnostic companies 46

Interference of heparin on DOAC specific assays Lessire S. et al. Clin App Thromb Hemost 2016. Accepted

Are the tests limited to specialized laboratories? NO!

Are the tests limited to specialized laboratories? NO! Weitz J, Eikelboom J. Circulation 2016

Interference of DOACs on various coagulation tests

Take home messages (1/4) 2 key opinion leaders says: Registration by regulatory agencies and their widespread implementation in clinical laboratories are “urgently” needed Dabigatran versus warfarin in patients with atrial fibrillation. Connolly SJ, Ezekowitz MD, Yusuf S, Eikelboom J, Oldgren J, Parekh A, Pogue J, Reilly PA, Themeles E, Varrone J, Wang S, Alings M, Xavier D, Zhu J, Diaz R, Lewis BS, Darius H, Diener HC, Joyner CD, Wallentin L; RE-LY Steering Committee and Investigators. N Engl J Med. 2009 Sep 17;361(12):1139-51. Idarucizumab for Dabigatran Reversal. Pollack CV Jr, Reilly PA, Eikelboom J, Glund S, Verhamme P, Bernstein RA, Dubiel R, Huisman MV, Hylek EM, Kamphuisen PW, Kreuzer J, Levy JH, Sellke FW, Stangier J, Steiner T, Wang B, Kam CW, Weitz JI. N Engl J Med. 2015 Aug 6;373(6):511-20. 51

Take home messages (2/4) DOACs are now cornerstones in the treatment of various thromboembolic diseases Although routine assessment of the intensity of anticoagulation is not required with these drugs, several situations may require the use of coagulation testing 52

Take home messages (3/4) aPTT should not be used except for screening a bleeding patient on dabigatran etexilate Normal APTT and/or PT don’t exclude presence of therapeutic levels Normal TT excludes clinical relevant drug level of dabigatran dTT and ECA should be preferred for normal and high concentrations (ECT is not recommended) Adaptations of the assays are required for low concentrations (perioperative management, reversal by idarizucimab) Importance of delay between last administration and sampling 53

Take home messages (4/4) How to interpret DOACs assays in urgent situations? 3 cut-offs: 30 – 50 – 200 ng/mL Use the appropriate assay (Laboratories): limit of quantitation, linearity ad interferences

Perspectives Development of point of care devices Development of a reference international calibrator Collect data about sample stability are lacking To validate low methodologies for apixaban and edoxaban in a perioperative setting To optimize the specificity of chromogenic assays for low DOACs plasma concentrations To reduce the turn-around time (TAT) of urgent DOAC level estimation To analyze the value of DOAC measurements in patients in emergency setting

Thank you for your attention

Acknowledgments Dr. Jonathan Douxfils Dr. Sarah Lessire Dr. Anne-Sophie Dincq Ph. Anne-Sophie Larock Ph. Anne-Laure Sennesael Dr. Bérangère Devalet Dr. Valérie Mathieux Pr. Bernard Chatelain Pr. Christian Chatelain Mrs. Justine Baudar Mrs. Maité Guldenpfennig Pr. Paul Hjemdahl Pr. Pierre Wallemacq Pr. Jean-Michel Dogné Dr Anne Godier Dr Isabelle Gouin-Thibault