title: A normal platelet count may not be enough: the impact of admission platelet count on mortality and transfusion in severely injured trauma patients.
abstract: BACKGROUND
  Platelets 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.
  
  
  METHODS
  A 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.
  
  
  RESULTS
  For 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.
  
  
  CONCLUSIONS
  Admission 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.
authors.affiliation: Department of Surgery, University of California, San Francisco, California, USA. lisa.brown@ucsfmedctr.org
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Brown
authors.forename: Mariah S
authors.initials: MS
authors.lastname: Call
authors.forename: M
authors.initials: M
authors.lastname: Margaret Knudson
authors.forename: Mitchell J
authors.initials: MJ
authors.lastname: Cohen
authors.forename: J B
authors.initials: JB
authors.lastname: Holcomb
authors.forename: C E
authors.initials: CE
authors.lastname: Wade
authors.forename: K J
authors.initials: KJ
authors.lastname: Brasel
authors.forename: G
authors.initials: G
authors.lastname: Vercruysse
authors.forename: J
authors.initials: J
authors.lastname: MacLeod
authors.forename: R P
authors.initials: RP
authors.lastname: Dutton
authors.forename: J R
authors.initials: JR
authors.lastname: Hess
authors.forename: J C
authors.initials: JC
authors.lastname: Duchesne
authors.forename: N E
authors.initials: NE
authors.lastname: McSwain
authors.forename: P
authors.initials: P
authors.lastname: Muskat
authors.forename: J
authors.initials: J
authors.lastname: Johannigamn
authors.forename: H M
authors.initials: HM
authors.lastname: Cryer
authors.forename: A
authors.initials: A
authors.lastname: Tillou
authors.forename: J F
authors.initials: JF
authors.lastname: Pittet
authors.forename: M A
authors.initials: MA
authors.lastname: De Moya
authors.forename: M A
authors.initials: MA
authors.lastname: Schreiber
authors.forename: B
authors.initials: B
authors.lastname: Tieu
authors.forename: S
authors.initials: S
authors.lastname: Brundage
authors.forename: L M
authors.initials: LM
authors.lastname: Napolitano
authors.forename: M
authors.initials: M
authors.lastname: Brunsvold
authors.forename: M
authors.initials: M
authors.lastname: Brunsvold
authors.forename: G
authors.initials: G
authors.lastname: Beilman
authors.forename: A B
authors.initials: AB
authors.lastname: Peitzman
authors.forename: M S
authors.initials: MS
authors.lastname: Zenait
authors.forename: J
authors.initials: J
authors.lastname: Sperry
authors.forename: L
authors.initials: L
authors.lastname: Alarcon
authors.forename: M A
authors.initials: MA
authors.lastname: Croce
authors.forename: J P
authors.initials: JP
authors.lastname: Minei
authors.forename: R
authors.initials: R
authors.lastname: Kozar
authors.forename: E A
authors.initials: EA
authors.lastname: Gonzalez
authors.forename: R M
authors.initials: RM
authors.lastname: Stewart
authors.forename: S M
authors.initials: SM
authors.lastname: Cohn
authors.forename: J E
authors.initials: JE
authors.lastname: Mickalek
authors.forename: E M
authors.initials: EM
authors.lastname: Bulger
authors.forename: B A
authors.initials: BA
authors.lastname: Cotton
authors.forename: T C
authors.initials: TC
authors.lastname: Nunez
authors.forename: R
authors.initials: R
authors.lastname: Ivatury
authors.forename: J W
authors.initials: JW
authors.lastname: Meredith
authors.forename: P
authors.initials: P
authors.lastname: Miller
authors.forename: G J
authors.initials: GJ
authors.lastname: Pomper
authors.forename: B
authors.initials: B
authors.lastname: Marin
mesh_terms: D000328:Adult; D001803:Blood Transfusion; D003955:Diagnostic Tests, Routine; D004636:Emergency Service, Hospital; D005260:Female; D006470:Hemorrhage / Q000097:blood* / Q000401:mortality* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D016896:Treatment Outcome; D014947:Wounds and Injuries / Q000097:blood* / Q000401:mortality* / Q000628:therapy