429 Risk of Intracerebral Hemorrhage on Repeat Head Computed Tomography Scan in Anticoagulated Patients

Abstract

Study Objectives: To identify the risk of intracerebral hemorrhage (ICH) for patients with minor head trauma taking warfarin or clopidogrel, and have an initial cranial computed tomography scan (CT) that is negative for ICH. Secondarily, to determine any risk factors associated with intracerebral hemorrhage in this population. Methods: Design: A retrospective chart review. Setting: Kaiser Permanente Southern California. Subjects: Adult patients seen at a Kaiser emergency department between 2007 and 2011, on warfarin with INR > 1.2 or clopidogrel, diagnosed with minor head trauma based on ICD9 codes, and had at least an initial CT. Pregnant women were excluded. The Health Connect database was utilized to identify patients. Patient charts were individually reviewed to determine CT results and gather other clinical data to determine factors associated with risk of ICH. If no follow-up scan was performed medical records were examined to ensure there was no intracerebral hemorrhage or mortality at 3 months from initial visit. Primary outcome measure: intracerebral hemorrhage on subsequent CT after an initially negative CT. Risk of delayed intracerebral hemorrhage as well as secondary analyses of clinical factors were determined using Poisson regression with robust error estimation. Results: Data were obtained on 201 patients. 130 were on warfarin and 71 on clopidogrel. Ages ranged from 24 to 97 with a median of 79. 101 (50.3%) patients were female. Initial CT was positive in 19 patients (9.5%). 29 of the 182 patients with an initial negative CT had a second CT performed. Of the 153 without a second CT, 137 were either well at 3-month follow-up or died of other causes. 15 did not have any follow-up data available. Thus 167 patients had complete data and an initial negative CT. 3 of these patients developed intracerebral hemorrhage on subsequent CT (1.7%, CI 1.68 - 1.72). Two were on warfarin (1.9%, CI 1.87 - 1.93) and one on clopidogrel (1.7%, CI 1.67 - 1.73). No clinical factors were significantly associated with ICH: INR (p = 0.72), loss of consciousness (p = 0.62), external evidence of head trauma (p = 0.72), vomiting (p = 0.89), and amnesia (p = 0.65). Conclusion: Anticoagulated patients with minor head trauma are at risk for development of intracerebral hemorrhage after an initial negative CT.