From Patti Richardson, St. Christopher’s Hospital for Children:
Good afternoon, George: For critical values, are pediatric hospitals using the prothrombin time and international normalized ratio (PT & INR)? For pediatric hospitals, what is the INR critical value most often used?
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Here is a Medpage article that broke July 23 describing the concern that Boehringer Ingelheim may have withheld data that supported dabigatran measurement in atrial fibrillation treatment. For the details, see Reilly PA, Lehr T, Haertter S, et al. The effect of dabigatran plasma concentrations and patient characteristics on the frequency of ischemic stroke and major bleeding in atrial fibrillation patients. JACC 2014;63:321–8. For a provocative read, see Cohen D. Dabigatran: how the drug company withheld important analysis. BMJ 2014;349,g4670 (epub).
George is seeking advice on behalf of a colleague. A 78-YO male patient with atrial fibrillation on Coumadin >20 years experiences a large bruise following a fall. The INR is 1.8. The patient also has Parkinson disease >10 years. Would you discontinue Coumadin? Would you propose alternative antithrombotic therapy? Thank you.
Biogen Idec released Alprolix®, their prolonged circulation recombinant factor IX concentrate soon after it was cleared by the FDA, March 28, 2014. Alprolix may be administered as little as once a week when used for factor IX deficiency (Hemophilia B) prophylaxis. The concentrate’s pharmacokinetics and efficacy were established using the partial thromboplastin time (PTT), identified as the “one-stage clotting assay (OSC)” by the distributor.
Buyue Y and Sommer JM, Biogen Idec, presented the poster referenced in the attached abstract at the International Society on Thrombosis and Hemostasis Standardization Subcommittee meeting in Milwaukee, June 23–25, 2014 describing the relative sensitivities of three PTT reagents, one each using ellagic acid, kaolin, or silica and concluded the ellagic acid-based is more sensitive than the others, indicating that the type of PTT reagent you use profoundly affects your factor assay results. Read more »
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.
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Thanks to Elaine Benoit at Precision BioLogic for this heads-up on the results of a new study describing dabigatran (Pradaxa) efficacy and safety outcomes in an older population, including a description of the risks of GI bleeding.
From Vanessa Chan at Sick Kids in Toronto: Hi George and the coag world, what assay is everyone using to monitor unfractionated heparin (UFH) and low molecular weight heparin (LMWH)? What are everyone’s thoughts on the use of antithrombin and/or dextran sulfate in these reagents? In your external quality assessments (EQAs), do you experience any biased results with your assays? Stago is replacing their AT-DS-Rotachrom reagent with Liquid Anti-Xa, I’m wondering if there are other AT-DS reagents available and what other labs suggest?
Thank you for the information, Vanessa. Participants, please provide your information.
From Kim Kinney, Indiana University, Hi George, one question leads to another. We have a meeting tomorrow (Tuesday, May 6) with our anticoagulation committee and one question that I think will come up will be, if we do convert to the chromogenic anti-Xa method for monitoring heparin, will we still maintain the therapeutic partial thromboplastin time (PTT, aPTT) range for those patients who must be monitored by the aPTT? For example, elevated bilirubin levels. It seems that doing this, at least from the lab’s standpoint, would not decrease lab costs or time involved in checking the PTT therapeutic range with each lot change. Sounds like that would need to be maintained. What are other institutions doing? As always, the input is appreciated.
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