Splenectomy is associated with hypercoagulable thrombelastography values and increased risk of thromboembolism

Abstract

Previous investigators have demonstrated that postinjury thrombocytosis is associated with an increase in thromboembolic (TE) risk. Increased rates of thrombocytosis have been found specifically in patients after splenectomy for trauma. We hypothesized that patients undergoing splenectomy (1) would demonstrate a more hypercoagulable profile during their hospital stay and (2) that this hypercoagulable state would be associated with increased TE events. This was a 14-month, prospective, observational trial evaluating serial rapid thrombelastography (rTEG) at 3 American College of Surgeons-verified, level 1 trauma centers. Inclusion criteria were highest-level trauma activation and arrival within 6hours of injury. Exclusion criteria were <18years of age, incarcerated, and burns>20% total body surface area. Serial rTEG (activated clotting time, k-time, α-angle, MA, lysis) and traditional coagulation testing (prothrombin time, partial thromboplastin time, fibrinogen and platelet count) were obtained at admission and then at 3, 6, 12, 24, 48, 72, 96, and 120hours. Thromboembolic complications were defined as the development of deep-vein thrombosis, pulmonary embolism, acute myocardial infarction, or ischemic stroke during hospitalization. Patients were stratified into splenectomy versus nonsplenectomy cohorts. Univariate analysis was then conducted followed by longitudinal analysis using generalized estimating equations to evaluate the effects of time, splenectomy, and group-time interactions on changes in rTEG and traditional coagulation testing. We used an adjusted generalized estimating equation model to control for age, sex, ISS, admission blood pressure, base deficit, and hemoglobin. A total of 1,242 patients were enrolled; 795 had serial rTEG data. Of these, 605 had serial values >24hours and made up the study population. Splenectomy patients were younger, more hypotensive, and in shock on arrival. Although there was no difference in 24-hour or 30-day mortality, splenectomy patients were more likely to develop TE events. Using the GEE model, we found that α-angle and MA in splenectomy patients were lesser (more hypocoagulable) within the first 6hours; however, they became substantially greater (more hypercoagulable) at 48, 72, 96, and 120hours; all P<.05. In addition, platelet counts were greater in the splenectomy group beginning at 72hours and continuing through 120hours; P<.05. This multicenter, prospective study demonstrates that patients undergoing splenectomy have a more hypercoagulable state than other trauma patients. This hypercoagulable state (identified by greater α-angle and mA values) begins at approximately 48hours after injury and continues through at least day 5. Moreover, this hypercoagulable state is associated with increased risk of TE complications.