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Survival analysis after head injury: is a normal INR reassuring?


Intracranial bleeding after head injury is an important issue in the emergency department (ED), and elevated INR increases this risk [1]. A retrospective study showed an association between different levels of normal INRs (<1.6) and elevated risk of intracranial bleeding, with a significant elevation of this risk over an INR threshold of 1.3 [2]. The objective of the study was to evaluate clinical impact of an INR within the normal range in patients with head trauma. We compared mortality between patients with INR <1.3 and those with INR ≥1.3 to <1.6.


A post hoc analysis of prospective data collected from 3,356 patients seen in a tertiary-care ED from March 2008 to February 2011. We included patients aged 16 years old and over with an INR <1.6 and a head CT performed within 24 hours of the trauma. We followed these patients until December 2012, performed a chi-square test between mortality of the two groups and calculated the hazard ratio (HR) from survival analysis using Cox regression.


Patient mean age was 55.1 years (SD ±23), 65% were men and mean follow-up duration was 3.1 years (SD ±0.8). A total of 115 patients (15.9%) died during follow-up: 16 (36.4%) in the group with INR ≥1.3 and 99 (14.6%) in the group with INR <1.3 (P < 0.001). Results showed a significantly higher risk of death in the group with INR ≥1.3: HR = 2.99 (95% CI = 1.8 to 5.1); P < 0.001 (Figure 1).


In patients with head injury and normal INR (<1.6), there is an association between an INR ≥1.3 and higher risk of death. Therefore, it would be useful to request an INR in patients presenting with a head injury when bleeding is suspected, even in the absence of anticoagulant.

Figure 1

Survival analysis of patients with INR <1.3 and with INR ≥1.3.


  1. 1.

    Lingsma HF, et al.: Early prognosis in traumatic brain injury: from prophecies to predictions. Lancet Neurol 2010, 9: 543-554. 10.1016/S1474-4422(10)70065-X

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    Chauny JM, et al.Non Elevated INR and Post Traumatic Intracranial Bleeding. Day of Research in Neurotraumatology. Montreal: Hôpital du Sacré-Cœur; 22 June 2012

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Correspondence to K Leclerc-Gagne.

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Leclerc-Gagne, K. Survival analysis after head injury: is a normal INR reassuring?. Crit Care 17, P336 (2013).

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  • Public Health
  • High Risk
  • Emergency Department
  • Retrospective Study
  • Emergency Medicine