Effect of platelet inhibition on bleeding complications in trauma patients on preinjury clopidogrel

J Trauma Acute Care Surg. 2013 Jun;74(6):1419-24. doi: 10.1097/TA.0b013e31828dac3e.


Background: Use of antiplatelet medications for acute coronary syndromes and stroke prevention continues to rise as the population ages, although their effects on trauma outcomes remain unclear. This study sought to determine if trauma patients on preinjury clopidogrel with a higher degree of platelet inhibition (PI), as determined by the VerifyNow P2Y12 Test, experienced bleeding complications more frequently than did patients with a lower degree of PI.

Methods: Retrospective, cohort study of adult trauma patients admitted to a Level 1 trauma center between October 1, 2009, and August 31, 2011, with documentation of clopidogrel as a home medication. Patients were excluded if they did not receive the P2Y12 assay, had a platelet count at the time of assay less than 100 × 10/L, or had warfarin, dabigatran, or other thienopyridine therapy documented as a concomitant home medication. The primary outcome compared a composite of bleeding complications between patients with 20% PI or greater and those with less than 20% PI. Bleeding complications were defined as the progression of neurologic insult, postoperative hemorrhage or initiation of the institutional massive blood transfusion protocol.

Results: Baseline characteristics were similar between groups. The incidence of bleeding complications was not different between study groups (24.2% vs. 27.6%, p = 0.78). No difference in the secondary outcomes of length of stay, in-hospital mortality, and red blood cell transfusion were observed. Patients with 20% PI or greater received platelet transfusion more frequently than did patients with less than 20% PI (51.5% vs. 10.3%, p = 0.0008).

Conclusion: The VerifyNow P2Y12 Test may be a tool to stratify trauma patients at a higher risk of bleeding and who subsequently may benefit from transfusion. More frequent platelet transfusion in patients with 20% PI or greater may have resulted in fewer bleeding complications, although confirmation in a prospective, randomized trial is warranted.

Level of evidence: Prognostic study, level III.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Platelets / drug effects*
  • Blood Platelets / physiology
  • Clopidogrel
  • Female
  • Hemorrhage / blood*
  • Hemorrhage / physiopathology
  • Humans
  • Male
  • Platelet Aggregation Inhibitors / adverse effects*
  • Platelet Function Tests
  • Receptors, Purinergic P2Y12 / physiology
  • Retrospective Studies
  • Ticlopidine / adverse effects
  • Ticlopidine / analogs & derivatives*
  • Wounds and Injuries / blood*
  • Wounds and Injuries / complications


  • P2RY12 protein, human
  • Platelet Aggregation Inhibitors
  • Receptors, Purinergic P2Y12
  • Clopidogrel
  • Ticlopidine