title: Assessing the effectiveness of whole blood-derived platelets stored as a pool: a randomized block noninferiority trial.
abstract: BACKGROUND
  Prestorage pooling of whole blood-derived platelets (PLTs) would simplify bacterial detection. This study evaluated the in vivo effect of the prestorage pooling of PLTs stored for up to 5 days, by assessing the corrected count increment (CCI) 18 to 24 hours after transfusion of the product.
  
  
  METHODS
  A randomized block noninferiority design was used. Eligible patients had chemotherapy-induced thrombocytopenia and were considered likely to need at least six PLT transfusions. For every block of two transfusion events, one consisted of PLTs stored individually and then pooled before transfusion, and the other was a product pooled before storage. The primary outcome was categorized as a successful (>4.5) or unsuccessful (<or=4.5) 18- to 24-hour posttransfusion CCI analyzed with a matched pair score test. A mixed-effect linear model estimated the mean difference in CCI between the two types of storage.
  
  
  RESULTS
  Twenty-three eligible patients received a total of 189 PLT transfusions. The median number of PLT transfusions was 7 (range, 0-27). Eighty-five complete transfusion pairs were used in the primary analysis. The proportions of transfusions leading to a CCI of greater than 4.5 was identical for both routine and PLTs pooled before storage (45/85=52.9%; relative risk, 1.00; lower limit of the one-sided 95% confidence interval [CI], 0.83). The estimate of the mean difference in CCI between pooled and routine storage (pooled-routine) was -0.45 (95% CI, -2.23 to 1.33; p=0.63).
  
  
  CONCLUSIONS
  These results provide evidence that storage of PLTs as a pool for up to 5 days results in posttransfusion CCIs that are not inferior to PLTs stored individually.
authors.affiliation: Department of Medicine and Pathology and Molecular Medicine, McMaster University, and the Canadian Blood Services, Hamilton, Ontario, Canada. heddlen@mcmaster.ca
authors.forename: N M
authors.initials: NM
authors.lastname: Heddle
authors.forename: R J
authors.initials: RJ
authors.lastname: Cook
authors.forename: M A
authors.initials: MA
authors.lastname: Blajchman
authors.forename: R L
authors.initials: RL
authors.lastname: Barty
authors.forename: C S
authors.initials: CS
authors.lastname: Sigouin
authors.forename: D M
authors.initials: DM
authors.lastname: Boye
authors.forename: E J
authors.initials: EJ
authors.lastname: Nelson
authors.forename: J G
authors.initials: JG
authors.lastname: Kelton
mesh_terms: D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000502:physiology*; D001793:Blood Preservation; D006801:Humans; D008875:Middle Aged; D010976:Platelet Count; D017713:Platelet Transfusion; D013921:Thrombocytopenia / Q000139:chemically induced / Q000628:therapy*; D013997:Time Factors