• Lisa M Brown, Mariah S Call, M Margaret Knudson, Mitchell J Cohen, Trauma Outcomes Group, J B Holcomb, C E Wade, K J Brasel, G Vercruysse, J MacLeod, R P Dutton, J R Hess, J C Duchesne, N E McSwain, P Muskat, J Johannigamn, H M Cryer, A Tillou, J F Pittet, M A De Moya, M A Schreiber, B Tieu, S Brundage, L M Napolitano, M Brunsvold, G Beilman, A B Peitzman, M S Zenait, J Sperry, L Alarcon, M A Croce, J P Minei, R Kozar, E A Gonzalez, R M Stewart, S M Cohn, J E Mickalek, E M Bulger, B A Cotton, T C Nunez, R Ivatury, J W Meredith, P Miller, G J Pomper, and B Marin.
• Department of Surgery, University of California, San Francisco, California, USA. lisa.brown@ucsfmedctr.org
• J Trauma. 2011 Aug 1;71(2 Suppl 3):S337-42.

BackgroundPlatelets play a central role in hemostasis after trauma. However, the platelet count of most trauma patients does not fall below the normal range (100-450 × 10(9)/L), and as a result, admission platelet count has not been adequately investigated as a predictor of outcome. The purpose of this study was to examine the relationship between admission platelet count and outcomes after trauma.MethodsA retrospective cohort study of 389 massively transfused trauma patients. Regression methods and the Kruskal-Wallis test were used to test the association between admission platelet count and 24-hour mortality and units of packed red blood cells (PRBCs) transfused.ResultsFor every 50 × 10(9)/L increase in admission platelet count, the odds of death decreased 17% at 6 hours (p = 0.03; 95% confidence interval [CI], 0.70-0.99) and 14% at 24 hours (p = 0.02; 95% CI, 0.75-0.98). The probability of death at 24 hours decreased with increasing platelet count. For every 50 × 10(9)/L increase in platelet count, patients received 0.7 fewer units of blood within the first 6 hours (p = 0.01; 95% CI, -1.3 to -0.14) and one less unit of blood within the first 24 hours (p = 0.002; 95% CI, -1.6 to -0.36). The mean number of units of PRBCs transfused within the first 6 hours and 24 hours decreased with increasing platelet count.ConclusionsAdmission platelet count was inversely correlated with 24-hour mortality and transfusion of PRBCs. A normal platelet count may be insufficient after severe trauma, and as a result, these patients may benefit from a lower platelet transfusion threshold. Future studies of platelet number and function after injury are needed.

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