The ever-increasing use of direct (or novel) oral anticoagulants (DOACs) has had a profound effect on primary and secondary prevention of thromboembolic events, especially in the elderly. Whilst many patients benefit from switching over to these newer drugs from older anticoagulants like warfarin, thus foregoing such nuisances as INR-guided dosing, they have also inevitably led to some new clinical questions. As we are seeing an increasing number of patients on DOACs in our traumatic brain injury population, it should prompt us ask the question: to which degree do they affect traumatic intracranial bleeding, compared to traditional drugs such as warfarin and anti-platelet agents?
This retrospective study by Prexl and colleagues in the SJTREM looked at 186 TBI patients 60 years-of-age or older. Patients were either on vitamin K antagonists (VKA), platelet-inhibitors, DOACs or taking no anticoagulant at all. The groups were largely comparable in severity and baseline characteristics. In line with previous studies they found that patients on a VKA had the highest mortality and the greatest risk of haematoma progression, whilst the risk of death was lowest in the DOAC group (even when compared to those on no anti-coagulants). This was in spite of the VKA group receiving a reversal agent (PCC) more often than the others. Length of stay in the ICU was similar in the groups.
Although the sample in this study is small, the findings match up quite well to those of most of the earlier studies on the subject, indicating that DOACs seemingly carry a somewhat lower TBI-related mortality and risk of worsening intracranial bleeding than older-generation anticoagulants. The exception being this study by Zeeshan et al showing increased mortality and haematoma growth in the DOAC-group. Their recruitment period seems to largely predate the introduction of specific DOAC-reversing agents, and in the subgroup with severe TBI there was no difference in any of the mentioned outcomes. Its results need to be interpreted with those limitations in mind. In future studies it would be interesting to see comparative studies that evaluate various DOACs up against each other, as there may be significant differences in risk profile. The increasing availability of specific reversal agents for a number of existing DOACs is promising and may help improve outcomes in TBI patients taking these drugs. But until these are widely available for all DOACs, work remains to be done in establishing a consensus-based protocol for management of TBI patients on these anticoagulants. When and how to reverse still varies significantly between centres.