Prevalence and Implications of Preinjury Warfarin Use

OBJECTIVES: To describe the prevalence of preinjury warfarin use in a large national sample of trauma patients and to define the relationship between preinjury warfarin use and mortality. DESIGN: Retrospective cohort study. SETTING: The National Trauma Databank (7.1). PATIENTS: All patients admitted to eligible trauma centers during the study period; 1,230,422 patients (36,270 warfarin users) from 402 centers were eligible for analysis. MAIN OUTCOME MEASURES: Prevalence of warfarin use and all-cause in-hospital mortality. Multivariate logistic regression was used to estimate the odds ratio (OR) for mortality associated with preinjury warfarin use. RESULTS: Warfarin use increased among all patients from 2.3% in 2002 to 4.0% in 2006 (P < .001), and in patients older than 65 years, use increased from 7.3% in 2002 to 12.8% in 2006 (P < .001). Among all patients, 9.3% of warfarin users died compared with only 4.8% of nonusers (OR, 2.02; 95% confidence interval CI, 1.95-2.10; P < .001). After adjusting for important covariates, warfarin use was associated with increased mortality among all patients (OR, 1.72; 95% CI, 1.63-1.81; P < .001) and patients 65 years and older (OR, 1.38; 95% CI, 1.30-1.47; P < .001). CONCLUSIONS: Warfarin use is common among injured patients and its prevalence has increased each year since 2002. Its use is a powerful marker of mortality risk, and even after adjusting for confounding comorbidities, it is associated with a significant increase in death.