ICH volume smaller with DOACs than with warfarin

Anna GarrettA recent study compared intracerebral hemorrhage (ICH) volume and clinical outcome of direct oral anticoagulants (DOAC) to warfarin-associated ICH. This multicenter study included 344 patients with anticoagulant-associated ICH. ICH volume was measured by an observer blinded to clinical details. Outcome measures were ICH volume and clinical outcome adjusted for confounding factors.

The study groups included 11 patients treated with DOACs and 52 patients with warfarin-ICH. The median ICH volume was 2.4 mL for DOAC ICH vs 8.9 mL for warfarin ICH. When data were adjusted for confounding factors (sex, hypertension, previous ischemic stroke, white matter disease burden, and premorbid modified Rankin Scale score [mRS]), warfarin use remained independently associated with larger ICH volumes. The data analysis also showed increased odds of a worse clinical outcome (as measured by discharge mRS) in warfarin ICH compared with DOAC ICH.

Source: Wilson D, Charidimou A, Shakeshaft C et al. Volume and functional outcome of intracerebral hemorrhage according to oral anticoagulant type. Neurology. 2016; 86:360–366.

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Faulty INR measures threaten ROCKET-AF trial

A faulty device used in the trial leading to approval of rivaroxaban has called those results into question, according to an investigation reported in The British Medical Journal.

The ROCKET-AF trial investigators distributed the point-of-care device (Alere INRatio) to measure international normalized ratios (INRs) for patients treated with warfarin, the comparator drug. FDA has since recalled the machine because of the potential for falsely low INR readings. Patients in the trial who had a low reading may have had warfarin doses increased unnecessarily, resulting in more bleeding episodes that made rivaroxaban use look safer.

The BMJ reports that in a letter to the New England Journal of Medicine, which published the ROCKET-AF results in 2011, the trial's authors present a reanalysis of their data and conclude that use of the device "did not have any significant clinical effect on the primary efficacy and safety outcomes in the trial."

Source: Cohen D. Rivaroxaban: Can we trust the evidence? BMJ. 2016;352:i575.

See also: Andexanet quickly reverses factor Xa inhibitor activity for DOACs

Stopping bleeds: Weight-based prothrombin vs. FFP

A small retrospective case-control study suggests that warfarin-induced coagulopathy reverses more quickly under a regimen of weight-based factor VIII inhibitor bypassing activity than with fresh frozen plasma.

Patients with life-threatening bleeds who were on warfarin prior to admission and who were treated with a weight-based activated prothrombin complex concentrate achieved reversal of their INR significantly faster than patients who received fresh frozen plasma only.

In the study, twenty-seven patients received factor VIII inhibitor bypassing activity and 27 received fresh frozen plasma. The mean dose of factor VIII inhibitor bypassing activity was 4,310 units, with a weight-based dose of 54 units/kg. The median use of fresh frozen plasma was 3 units, with a volume of 790 mL.

The median baseline INR was 3.7 in patients who received factor VIII inhibitor bypassing activity and 2.8 in those who received fresh frozen plasma.

Vitamin K was administered to fewer patients treated with factor VIII inhibitor bypassing activity vs. patients given fresh frozen plasma (81% vs 93%).

The median time to achieve an INR below 1.5, the primary end point, was significantly faster with factor VIII inhibitor bypassing activity than with fresh frozen plasma (2.4 vs. 12.0 hours).

The number of thromboembolic events and overall mortality were not significantly different between groups.

Source: Lowry F. Weight-based prothrombin stops warfarin-induced bleeding. Medscape Medical News. http://www.medscape.com/viewarticle/859791#vp_2. Accessed March 4, 2016.