Study Challenges Assumption That Warfarin Raises Brain Bleed Risk After Falls

A study has challenged the long-standing belief that older adults taking warfarin with high International Normalized Ratio (INR) levels are at increased risk of brain bleeding after falls. Researchers at Florida Atlantic University’s Charles E. Schmidt College of Medicine conducted a one-year investigation at two Level I trauma centers in South Florida, analyzing data from 2,686 adults aged 65 and older admitted after fall-related head injuries.

Falls and anticoagulant use in older adults

Falls remain a significant health concern for older adults. They are the leading cause of injury and death in this population, contributing to 38,000 fatalities and 3 million emergency department visits in the United States in 2021. Non-fatal falls cost an estimated $80 billion in 2020, an increase from 2015. As age-related cardiovascular and cerebrovascular conditions become more prevalent, many older adults are prescribed blood thinners such as warfarin to prevent clot-related complications.

While anticoagulants effectively reduce the risk of stroke and other vascular events, they raise concerns in the context of head trauma because of their potential to increase bleeding risk. Clinical guidelines often recommend heightened monitoring, repeat brain imaging, and hospital admission for older adults on warfarin who sustain head injuries, based on the assumption that higher INR levels correlate with greater risk of intracranial hemorrhage.

Examining INR levels and outcomes

The researchers aimed to clarify whether very high INR levels truly increase the likelihood of brain bleeding after head trauma in older adults on warfarin. They reviewed patient medical histories, laboratory results, imaging findings from computed tomography (CT) scans, and clinical outcomes. Patients were followed for 14 days to detect any delayed intracranial bleeding.

Among all participants, 11% experienced brain bleeding. For those not on blood thinners, the rate was 6%, while 7% of those on warfarin developed hemorrhage. Importantly, no statistically significant difference was found in bleeding rates between patients with INR levels above 3.0 and those within or below the therapeutic range. Unexpectedly, patients with INR below the recommended range faced the highest bleeding risk, at nearly 20%. By contrast, no intracranial hemorrhages were reported in patients with INR levels above 5.

Reconsidering current emergency protocols

These results suggest that supratherapeutic INR levels may not increase the risk of brain bleeding as much as previously assumed. Instead, subtherapeutic anticoagulation appeared associated with higher rates of hemorrhage, highlighting the importance of effective medication management rather than avoidance of anticoagulation therapy.

The findings challenge current emergency care practices, which often include prolonged observation and repeated CT scans for all older adults on warfarin who sustain head injuries. Re-evaluating these protocols could help reduce unnecessary hospital stays and imaging use while focusing care on patients most likely to benefit from intervention.

Implications for clinical practice

The study emphasizes the need for evidence-based risk assessment in managing fall-related head trauma in older adults taking anticoagulants. Improved understanding of how INR levels relate to bleeding risk may allow clinicians to make more precise decisions on monitoring and follow-up care.

In regions like South Florida, where the population of older adults is expanding, the study’s findings have practical implications for resource allocation in emergency departments. Targeted monitoring strategies could balance patient safety with efficiency in care delivery.

Reference: Caplan C, Engstrom G, Wells M, et al. Supratherapeutic warfarin and risk of intracranial hemorrhage in geriatric patients with blunt head trauma. Am J Emerg Med. 2025. doi: 10.1016/j.ajem.2025.06.020

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