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Minor head injury in warfarinized patients: indicators of risk for intracranial hemorrhage.

BACKGROUND
Head injury represents one of the most important and frequent traumatic pathology in the emergency department. Among the different risk factors, preinjury use of warfarin has received considerable attention in trauma literature. The aim of this study was to identify further risk indicators of intracranial hemorrhage (ICH) to improve risk stratification of warfarinized patients with minor head injuries.


METHODS
Medical records of 1,554 adult patients with minor head injuries evaluated by the Emergency Department of Azienda Ospedaliera, Universitaria Careggi from January 2007 to February 2008 were analyzed retrospectively. All the patients included in the study were subjected to blood tests. The international normalized ratio (INR) measured on admission was correlated with the results of head computed tomography scan.


RESULTS
Of the 1,410 patients included in the study, 75 (5.2%) were warfarin anticoagulated at the time of trauma. The INR measured on admission was 2.37 ± 1.04 (mean ± standard deviation), and this value was significantly associated with occurrence of ICH after head trauma (r = 0.37; p < 0.005). For 12 (of 75) patients of this group, the findings of the computed tomography scans were positive. The receiver operating characteristic curve show that the most effective INR cutoff value was 2.43, with a sensitivity of 92%, a specificity of 66%, and positive and negative predictive values of 33% and 97%, respectively.


CONCLUSIONS
This study highlights the strong relationship between INR values and the probability of ICH, as shown in previous studies. The high negative predictive value of the identified cutoff, if confirmed, could be used to exclude ICH.