Register Login

Assays for Direct Oral Anticoagulants

From Lisa Bakken:

I am a part of a stroke committee at my hospital that needs/wants to implement anti-factor Xa and anti-factor IIa testing for the new oral anticoagulants (NOACs). In addition to this, our laboratory is looking into new coag instrumentation. We are struggling to determine what is the best for our patient population. Our geriatric population is particularly high so the need for monitoring anti-thrombolytics and stroke work-ups will be high.
Hemostasis is not my strong suit and I value your opinion. May I ask what instrumentation do you use in your laboratory? We currently have a CA-1500 from Siemens and we were looking at the Stago STA Compact Max. Are you familiar with either platform? Do you think the Stago reagents for the NOACs are better or worse than what Siemens has? Which methodology do you feel is more accurate, optical or mechanical? It’s always difficult when trying to discern information from sales representatives from both companies. Any insight you can give would be appreciated.

Hello, Lisa, and thank you for your question. First a disclaimer, I always avoid sharing my instrument and reagent comparison opinions. However, I invite our participants, who include experienced laboratory practitioners and trusted account managers fromSiemensIL, and Stago, to respond either in the comments section below or by writing to me privately at [email protected]. I will forward comments sent to my email address directly to Lisa.

On to some first-hand information. Our University of Alabama at Birmingham Hospital coagulation laboratory has used Stago instrumentation for many years, starting with the STA. We’ve had two STARs for several years and they remain functional. I hear from others who are satisfied with their IL and Siemens (who also distribute the Sysmex CA Series) instrumentation as well.

Both optical and mechanical instruments provide good reproducibility and are relatively stable. The optical method is sometimes criticized for being unable to provide accurate time intervals for lipemic specimens, although IL seems to have partially resolved this problem in their high-end instruments by employing long wavelength light sources. It may be that the desktop instruments don’t offer this feature.

Several experts, realizing the NOACs won’t be new for much longer, have chosen to name them direct oral anticoagulants (DOACs) or target-specific anticoagulants (TSOACs). The direct anti Xa oral anticoagulantsrivaroxaban (Xarelto)apixaban (Eliquis), and soon to be released edoxaban (Lixiana) are  measured using the standard chromogenic anti-Xa heparin assay modified to use specific calibrators derived from the drugs. Stago and Aniara (Hyphen BioMed) offer both rivaroxaban and apixaban calibrators, however they await FDA clearance. Until these are cleared, if your institution prefers not to employ research use only assays, the prothrombin time can be used to provide a “poor man’s” qualitative assay. See…

  • Samama MM, Contant G, Spiro TE, et al; Rivaroxaban Anti-Factor Xa Chromogenic Assay Field Trial Laboratories. Evaluation of the anti-factor Xa chromogenic assay for the measurement of rivaroxaban plasma concentrations using calibrators and controls. Thromb Haemost. 2012;107:379–87.
  • Samama MM, Contant G, Spiro TE, et al; Rivaroxaban Prothrombin Time Field Trial Laboratories. Evaluation of the prothrombin time for measuring rivaroxaban plasma concentrations using calibrators and controls: results of a multicenter field trial. Clin Appl Thromb Hemost. 2012;18:150–8.
  • Adcock DM, Gosselin R, Kitchen S, Dwyre DM. The effect of dabigatran on select specialty coagulation assays. Am J Clin Pathol. 2013;139:102–9.
  • Fritsma GA. Monitoring the anti-Xa anticoagulants, from heparin to eliquis. Clin Lab Sci. 2013;26:48–53.

Dabigatran (Pradaxa), FDA-cleared in 2009, is a direct thrombin inhibitor. Two assays provide accurate and linear results. The Hemoclot Thrombin Inhibitors Assay distributed by Aniara, a simple clot-based plasma-diluted thrombin time assay, and Stago’s Ecarin chromogenic assay (ECA). Both are awaiting FDA clearance, and meanwhile, lab directors may use the activated partial thromboplastin time assay which gives semiquantatitive results, or the standard thrombin time, which provides a qualitative result. See…

  • Fritsma GA. Monitoring the direct thrombin inhibitors. Clin Lab Sci. 2013;26:54–7.
  • McGlasson DL, Fritsma GA, Ezzell EE, Anderson NA. Comparison of four dabigatran assays in an anticoagulant clinic population. Abstract 139. Am J Hematol 2014;89:E67.

Also, the attached poster, which appears next week at the ISTH SSC meeting in Milwaukee, illustrate the possibility of employing the dilute Russell viper venom confirmatory reagent to measure dabigatran:
Dabi DRVVC Poster

Finally, there is no dedicated assay for measuring anti-thrombolytics such as tranexamic acid (Cyclokapron), although some advocate for the automated D-dimer assay. Perhaps the most reported means for measuring anti-thrombolytics is thromboelastography (Thromboelastograph) or thromboelastometry (ROTEM). See…

  • Dirkmann D, Radü-Berlemann J, Görlinger K, Peters J. Recombinant tissue-type plasminogen activator-evoked hyperfibrinolysis is enhanced by acidosis and inhibited by hypothermia but still can be blocked by tranexamic acid. J Trauma Acute Care Surg. 2013;74:482–8.
Comments (0)
Anticoagulant Therapy

No comments here.

Leave a Reply