Hypercoagulability is most prevalent early after injury and in female patients.

BACKGROUND: Hypercoagulability after injury is a major source of morbidity and mortality. Recent studies indicate that there is a gender-specific risk in trauma patients. This study was performed to determine the course of coagulation after injury and to determine whether there is a gender difference. We hypothesized that hypercoagulability would occur early after injury and that there would be no difference between men and women.
METHODS: This was a prospective cohort study. Inclusion criteria were admission to the intensive care unit, Injury Severity Score > 4, and the ability to obtain consent from the patient or a relative. A Thrombelastograph (TEG) analysis was performed and routine coagulation parameters and thrombin-antithrombin complexes were measured within 24 hours of injury and then daily for 4 days.
RESULTS: Sixty-five patients met criteria for entry into the study. Their mean age was 42 +/- 17 years and their mean Injury Severity Score was 23 +/- 12. Forty patients (62%) were men. The prevalence of a hypercoagulable state by TEG was 62% on day 1 and 26% on day 4 (p < 0.01). Women were significantly more hypercoagulable on day 1 than men as measured by the time to onset of clotting (women, 2.9 +/- 0.7 minutes; men, 3.9 +/- 1.5 minutes; p < 0.01; normal, 3.7-8.3 minutes). Mean platelet counts, international normalized ratios, and partial thromboplastin times were within normal limits throughout the study. Thrombin activation as measured by thrombin-antithrombin complexes decreased from 34 +/- 15 microg/L on day 1 to 18 +/- 8 microg/L (p < 0.01) on day 4, consistent with the prevalence of hypercoagulability by TEG.
CONCLUSION: Hypercoagulability after injury is most prevalent during the first 24 hours. Women are more hypercoagulable than men early after injury. The TEG is more sensitive than routine coagulation assays for the detection of a hypercoagulable state.