Repeat CT may be needed after head trauma in patients on older blood thinning meds

Patients on older antiplatelet or anticoagulant agents who sustain head trauma may be at an increased risk of delayed post-traumatic intracranial haemorrhage (ICH) than those on direct oral anticoagulants (DOACs), according to a retrospective study presented at RSNA 2021.

“DOACs demonstrated significantly lower risk of both [delayed ICH] and mortality than warfarin/clopidogrel,” said study author Dr Warren Chang, director of research at the Imaging Institute of the Allegheny Health Network, Pittsburgh, Pennsylvania, US, and co-authors.

“Repeat head CT should be considered on trauma patients on anticoagulant/antiplatelet medications, especially warfarin and/or clopidogrel,” they suggested.

Chang and co-authors pulled data from the Allegheny Health Network to identify patients who were on antiplatelets or anticoagulants (including DOACs), experienced head trauma, and who underwent CT imaging between January 1, 2017 and January 1, 2020. They included 1,046 patients (average age 77.5 years, 547 female) whose initial CT imaging was negative for ICH and who underwent a repeat CT scan with no additional trauma between imaging tests. Of these, 470 were on older blood thinning medications.

Patients whose initial imaging test was retrospectively identified as positive were excluded. Patients whose second CT test identified an ICH following a negative first CT scan were categorized as positive. Conversely, cases were categorized as negative if ICH on the second CT imaging test was deemed absent or artifactual.

Delayed ICH was identified in 1.91 percent of patients (n=20), with an overall mortality rate of 0.3 percent (n=3). [RSNA 2021, session SSNR08-6]

Patients on warfarin or clopidogrel had a higher rate of delayed ICH compared with patients on DOACs (3.2 percent vs 0.9 percent; p<0.01). All deaths occurred among patients in the clopidogrel/warfarin/older blood thinner group. 

A total of 345 patients were on both blood thinning medications and aspirin. Of the 20 patients with delayed ICH, 15 were taking older blood thinning medications, nine of whom were also on aspirin. Among the five patients with delayed ICH who were on DOACs, four were also on aspirin.

“The rate of delayed haemorrhage was higher in patients taking older blood thinners compared to novel drugs, and significantly higher in patients taking aspirin in addition to the older medications,” noted Chang.

“Taking any blood thinner concurrently with aspirin significantly increased the risk of delayed haemorrhage, while taking one of the novel medications without aspirin significantly reduced the risk,” he continued.

“The incidence of delayed post-traumatic ICH in patients on different types of blood thinners with and without the addition of aspirin is not well established,” Chang explained. “This is an active area of investigation, especially as novel blood thinners become more widely adopted.”

Although patients on blood thinners who experience head trauma are subjected to an initial CT scan of the brain, the standard of care beyond this initial investigation tends to vary between hospitals.

“Given the high volume of our trauma patients taking aspirin and anticoagulants, this study will help to guide our care of closed head injury patients in emergency medicine and support efforts to use imaging resources appropriately,” commented Dr Thomas Campbell, system chair for Emergency Medicine of the Allegheny Health Network.

The authors recommended that patients on older blood thinners who experience head trauma should undergo a repeat CT scan even if their initial scan showed no sign of ICH. The repeat CT should be also be done for patients who take any blood thinner in combination with aspirin. Conversely, repeat CT may be unnecessary for patients on newer blood thinning medications who are not on aspirin, except if there are external signs of trauma.