H. H. Hon1, A. Elmously1, C. D. Stehly1,2, J. Stoltzfus3, S. P. Stawicki1,2, B. A. Hoey1 1St. Luke’s University Health Network,Regional Level I Trauma Center,Bethlehem, PA, USA 2St. Luke’s University Health Network,Department Of Research & Innovation,Bethlehem, PA, USA 3St. Luke’s University Health Network,The Research Institute,Bethlehem, PA, USA
Introduction: Warfarin continues to be widely prescribed in the United States for a variety of conditions. Several studies have demonstrated that pre-injury warfarin may worsen outcomes in trauma patients. We hypothesized that a substantial proportion of our trauma population was receiving pre-injury warfarin for inappropriate indications and that a significant number of such patients had subtherapeutic or supratherapeutic international normalized ratios (INR). Our secondary aim was to determine if pre-injury warfarin is associated with increased mortality.
Methods: A 10-year retrospective review of registry data from a Level I trauma center was conducted between 2004 and 2013. Abstracted variables included patient age, Injury Severity Score (ISS), Abbreviated Injury Score (AIS) for head, mortality, hospital length of stay (HLOS), indication(s) for anticoagulant therapy, admission Glasgow Coma Scale, and admission INR determinations. Warfarin indication(s) and suitability were verified using the most recent American College of Chest Physicians (ACCP) Guidelines. Inappropriate warfarin administration was defined as use inconsistent with ACCP guidelines. For outcome comparisons, a random sample of trauma patients who were not taking warfarin was designated as "control group". Additionally, severe traumatic brain injury (sTBI) was defined as AIS head ≽4. Statistical analyses were conducted using the chi-square and the Mann-Whitney rank sum tests, as appropriate.
Results: A total of 21,136 blunt trauma patients were evaluated by the trauma service during the study period. Of those 1,481 (7%) were receiving warfarin prior to injury, with an additional 1,947 (~10% of the non-warfarin sample) designated as "non-warfarin controls". According to the ACCP Guidelines, 264/1,481 (17.8%) patients in the warfarin group were receiving anticoagulation inappropriately. Moreover, >63% of the patients were outside of the intended therapeutic window with regard to their INR (41.1% subtherapeutic, 22.2% supratherapeutic). Overall, median HLOS was greater in patients taking pre-injury warfarin (4 days vs. 2 days, p <0.01). Mortality was higher in the warfarin group (6.1% or 91/1,481) vs. the control group (2.6% or 50/1,947, p<0.01). Patients with sTBI (AIS head ≽4) were had significantly greater mortality in the warfarin group (26.4% or 56/212) vs. the control group (14.9% or 22/148, p<0.01).
Conclusion: A significant number of trauma patients admitted to our institution were noted to take warfarin for inappropriate indications. Moreover, a significant proportion of patients taking warfarin had either subtherapeutic or supratherapeutic INRs. Pre-injury warfarin was associated with increased mortality and HLOS in this study, especially in the subset of patients with sTBI. National safety initiatives directed at appropriate initiation and management of warfarin are necessary.