Study Objective
Patients on warfarin or clopidogrel are considered at increased risk for traumatic intracranial hemorrhage (tICH) following blunt head trauma. The prevalence of immediate tICH and the cumulative incidence of delayed tICH in these patients, however, are unknown.
Methods
A prospective, observational study at two trauma centers and four community hospitals enrolled emergency department (ED) patients with blunt head trauma and pre-injury warfarin or clopidogrel use from April 2009 through January 2011. Patients were followed for two weeks. The prevalence of immediate tICH and the cumulative incidence of delayed tICH were calculated from patients who received an initial cranial computed tomography (CT) in the ED. Delayed tICH was defined as tICH within two weeks following an initially normal CT scan and in the absence of repeat head trauma.
Results
A total of 1,064 patients were enrolled (768 warfarin patients [72.2%] and 296 clopidogrel patients [27.8%]). There were 364 patients [34.2%] from Level 1 or 2 trauma centers and 700 patients [65.8%] from community hospitals. One thousand patients received a cranial CT scan in the ED. Both warfarin and clopidogrel groups had similar demographic and clinical characteristics although concomitant aspirin use was more prevalent among patients on clopidogrel. The prevalence of immediate tICH was higher in patients on clopidogrel (33/276, 12.0%; 95% confidence interval [CI] 8.4-16.4%) than patients on warfarin (37/724, 5.1%; 95%CI 3.6-7.0%), relative risk 2.31 (95%CI 1.48-3.63). Delayed tICH was identified in 4/687 (0.6%; 95%CI 0.2-1.5%) patients on warfarin and 0/243 (0%; 95%CI 0-1.5%) patients on clopidogrel.
Conclusion
While there may be unmeasured confounders that limit intergroup comparison, patients on clopidogrel have a significantly higher prevalence of immediate tICH compared to patients on warfarin. Delayed tICH is rare and occurred only in patients on warfarin. Discharging patients on anticoagulant or antiplatelet medications from the ED after a normal cranial CT scan is reasonable but appropriate instructions are required as delayed tICH may occur.