title: Aspirin as added prophylaxis for deep vein thrombosis in trauma: A retrospective case-control study.
abstract: BACKGROUND
  Current prophylaxis does not completely prevent deep vein thrombosis (DVT) in trauma patients. Recent data suggest that platelets may be a major contributor to hypercoagulability after trauma, indicating a potential role for antiplatelet medications in prophylaxis for DVT. We sought to determine if preinjury aspirin use was associated with a reduced incidence of lower extremity DVT in trauma patients.
  
  
  METHODS
  Using a retrospective case-control design, we matched 110 cases of posttrauma lower extremity DVT one-to-one with controls using seven covariates: age, admission date, probability of death, number of DVT risk factors, sex, mechanism of injury, and presence of head injury. Data collected included 26 risk factors for DVT, prehospital medications, and in-hospital prophylaxis. Logistic regression models were created to examine the relationship between prehospital aspirin use and posttrauma DVT.
  
  
  RESULTS
  Preinjury aspirin was used by 7.3% of cases (patients diagnosed with in-hospital DVT) compared with 13.6% of controls (p = 0.1). Aspirin was associated with a significant protective effect in multivariate analysis, with an odds ratio of 0.17 (95% confidence interval, 0.04-0.68; p = 0.012) in the most complete model. When stratified by other antithrombotic use, aspirin showed a significant effect only when used in combination with heparinoid prophylaxis (odds ratio, 0.35; 95% confidence interval, 0.13-0.93; p = 0.036).
  
  
  CONCLUSIONS
  Preinjury aspirin use seems to significantly lower DVT rate following injury. This association is strongest when heparinoid prophylaxis is prescribed after patients on preinjury aspirin therapy are admitted. Aspirin as added prophylaxis for DVT in trauma patients needs to be further evaluated.
  
  
  METHODS
  Prognostic and epidemiologic study, level III.
authors.affiliation: From the Trauma Service, Scripps Mercy Hospital, San Diego, California.
authors.forename: Jason B
authors.initials: JB
authors.lastname: Brill
authors.forename: Richard Y
authors.initials: RY
authors.lastname: Calvo
authors.forename: James D
authors.initials: JD
authors.lastname: Wallace
authors.forename: Paul R
authors.initials: PR
authors.lastname: Lewis
authors.forename: Vishal
authors.initials: V
authors.lastname: Bansal
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sise
authors.forename: Steven R
authors.initials: SR
authors.lastname: Shackford
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D020246:Venous Thrombosis / Q000209:etiology* / Q000517:prevention & control*; D014947:Wounds and Injuries / Q000150:complications*
chemical_list: D000925:Anticoagulants; D001241:Aspirin