Mild elevations of international normalized ratio at hospital Day 1 and risk of expansion in warfarin-associated subdural hematomas

Clinical article

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A primary goal in the treatment of patients with warfarin-associated subdural hematoma (SDH) is reversal of coagulopathy with fresh-frozen plasma. Achieving the traditional target international normalized ratio (INR) of 1.3 is often difficult and may expose patients to risks of volume overload and of thromboembolic complications. This retrospective study evaluates the risk of mild elevations of INR from 1.31 to 1.69 at 24 hours after admission in patients presenting with warfarin-associated SDH.


Sixty-nine patients with warfarin-associated SDH and 197 patients with non–warfarin-associated SDH treated at a single institution between January 2005 and January 2012 were retrospectively identified. Charts were reviewed for patient age, history of trauma, associated injuries, neurological status at presentation, size and chronicity of SDH, associated midline shift, INR at admission and at hospital Day 1 (HD1), concomitant aspirin or Plavix use, platelet count, and medical comorbidities. Patients were stratified according to use of warfarin and by INR at HD1 (INR 0.8–1.3, 1.31–1.69, 1.7–1.99, and ≥ 2). The groups were evaluated for differences the in rate of radiographic expansion of SDH and in the rate of clinically significant SDH expansion resulting in death, unplanned procedure, and/or readmission.


There was no difference in the rate of radiographic versus clinically significant expansion of SDH between patients not on warfarin and those on warfarin (no warfarin: 22.3% vs 20.3%, p = 0.866; warfarin: 10.7% vs 11.6%, p = 0.825), but the rate of medical complications was significantly higher in the warfarin subgroup (13.3% for patients who did not receive warfarin vs 26.1% for those who did; p = 0.023). For warfarin-associated SDH, there was no difference in the rate of radiographic versus clinically significant expansion between patients reversed to HD1 INRs of 0.8–1.3 and 1.31–1.69 (HD1 INR 0.8–1.3: 22.5% vs 20%, p = 1; HD1 INR 1.31–1.69: 15% vs 10%, p = 0.71).


Mild INR elevations of 1.31–1.69 in warfarin-associated SDH are not associated with a markedly increased risk of radiographic or clinically significant expansion of SDH. Larger prospective studies are needed to determine if subtherapeutic INR elevations at HD1 are associated with smaller increases in risk of SDH expansion.

Abbreviations used in this paper:FFP = fresh-frozen plasma; GCS = Glasgow Coma Scale; HD1 = hospital Day 1; INR = international normalized ratio; LOS = length of stay; SDH = subdural hematoma.

Article Information

Address correspondence to: Julian K. Wu, M.D., Department of Neurosurgery, Tufts Medical Center, 800 Washington Street, Boston, Massachusetts 02111. email:

Please include this information when citing this paper: published online April 12, 2013; DOI: 10.3171/2013.3.JNS121946.

© AANS, except where prohibited by US copyright law.



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    Chart showing patient selection methods.

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    Bar graph showing radiographic and clinically significant expansion rates of SDH based on warfarin use.

  • View in gallery

    Bar graph showing radiographic and clinically significant expansion rates of warfarin-associated SDH based on HD1 INR.



Appelboam RThomas EO: Warfarin and intracranial haemorrhage. Blood Rev 23:192009


Atrial Fibrillation Investigators: Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Analysis of pooled data from five randomized controlled trials. Arch Intern Med 154:144914571994. (Erratum in Arch Intern Med 154:2254 1994)


Bershad EMFarhadi SSuri MFFeen ESHernandez OHSelman WR: Coagulopathy and inhospital deaths in patients with acute subdural hematoma. Clinical article. J Neurosurg 109:6646692008


Beyth RJQuinn LMLandefeld CS: Prospective evaluation of an index for predicting the risk of major bleeding in outpatients treated with warfarin. Am J Med 105:91991998


Fihn SDCallahan CMMartin DCMcDonell MBHenikoff JGWhite RH: The risk for and severity of bleeding complications in elderly patients treated with warfarin. Ann Intern Med 124:9709791996


Fortuna GRMueller EWJames LEShutter LAButler KL: The impact of preinjury antiplatelet and anticoagulant pharmacotherapy on outcomes in elderly patients with hemorrhagic brain injury. Surgery 144:5986052008


Franko JKish KJO'Connell BGSubramanian SYuschak JV: Advanced age and preinjury warfarin anticoagulation increase the risk of mortality after head trauma. J Trauma 61:1071102006


IMS Institute for Healthcare Informatics: The Use of Medicines in the United States: Review of 2011 Parsippany, NJIMS Institute for Healthcare Informatics( [Accessed March 12 2013]


Ivascu FAHowells GAJunn FSBair HABendick PJJanczyk RJ: Rapid warfarin reversal in anticoagulated patients with traumatic intracranial hemorrhage reduces hemorrhage progression and mortality. J Trauma 59:113111392005


Landefeld CSBeyth RJ: Anticoagulant-related bleeding: clinical epidemiology, prediction, and prevention. Am J Med 95:3153281993


Larson BJGZumberg MSKitchens CS: A feasibility study of continuing dose-reduced warfarin for invasive procedures in patients with high thromboembolic risk. Chest 127:9229272005


Menzin JWhite LAFriedman MNichols CMenzin JHoesche J: Factors associated with failure to correct the international normalized ratio following fresh frozen plasma administration among patients treated for warfarin-related major bleeding. Thromb Haemost 107:6626722012


Mountain DSistenich VJacobs IG: Characteristics, management and outcomes of adults with major trauma taking preinjury warfarin in a Western Australian population from 2000 to 2005: a population-based cohort study. Med J Aust 193:2022062010


Oake NJennings AForster AJFergusson DDoucette Svan Walraven C: Anticoagulation intensity and outcomes among patients prescribed oral anticoagulant therapy: a systematic review and meta-analysis. CMAJ 179:2352442008


Oyama HKito AMaki HHattori KNoda TWada K: Acute subdural hematoma in patients with medication associated with risk of hemorrhage. Neurol Med Chir (Tokyo) 51:8258282011


Palareti GLeali NCoccheri SPoggi MManotti CD'Angelo A: Bleeding complications of oral anticoagulant treatment: an inception-cohort, prospective collaborative study (ISCOAT). Lancet 348:4234281996


Panczykowski DMOkonkwo DO: Premorbid oral antithrombotic therapy and risk for reaccumulation, reoperation, and mortality in acute subdural hematomas. Clinical article. J Neurosurg 114:47522011


Pieracci FMEachempati SRShou JHydo LJBarie PS: Degree of anticoagulation, but not warfarin use itself, predicts adverse outcomes after traumatic brain injury in elderly trauma patients. J Trauma 63:5255302007


Singer DEChang YFang MCBorowsky LHPomernacki NKUdaltsova N: Should patient characteristics influence target anticoagulation intensity for stroke prevention in nonvalvular atrial fibrillation? The ATRIA study. Circ Cardiovasc Qual Outcomes 2:2973042009




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