Utility of INR For Prediction of Delayed Intracranial Hemorrhage Among Warfarin Users with Head Injury

Incidence of delayed intracranial hemorrhage (DICH) in patients on warfarin has been controversial. No previous literature has reported the utility of international normalized ratio (INR) in predicting traumatic DICH.

Utilizing INR to risk stratify head trauma patients who may be managed without repeat imaging.

This was a retrospective study at a Level II trauma center. All patients on warfarin with head injuries from March 2014 to December 31, 2017 were included. Each patient underwent an initial head computed tomography scan (HCT) and subsequent repeat HCT 12 h after. Patients presenting > 12 h after head injury received only one HCT. Two blinded neuroradiologists reviewed each case of DICH. Statistical analysis evaluated Glasgow Coma Scale (GCS), Injury Severity Score (ISS), heart rate, systolic blood pressure (SBP), age, and platelet count.

There were 395 patients who qualified for the protocol; 238 were female. Average age was 79 years. Seventy-seven percent of patients underwent repeat HCT. Five resulted in DICH (INR 2.6-3.0), three of which might have been present on initial HCT; incidence rate of 0.51-1.27%. One patient required neurosurgical intervention. Among 80 patients with INR < 2, no DICH was identified, resulting in high sensitivity, but with a wide confidence interval; sensitivity of 100% (95% confidence interval [CI] 47.8-100), specificity 21% (95% CI 16.6-28.9). Correlation of factors: ISS (p = 0.039), GCS (p = 0.978), HR (p = 0.601), SBP (p = 0.198), age (p = 0.014), and platelets (p = 0.281).

No patient with INR < 2 suffered DICH, suggesting that warfarin users presenting with INR < 2 may be managed without repeat HCT. For INR > 2, patients age and injury severity can be used for shared decision-making to discharge home with standard head injury precautions and no repeat HCT.