Submitted September 15, 2008
Accepted December 15, 2008
A randomized controlled trial comparing standard and low-dose strategies for transfusion of platelets (SToP) to patients with thrombocytopenia
Nancy M Heddle*, Richard J Cook, Alan Tinmouth, C. Tom Kouroukis, Tor Hervig, Ellen Klapper, Joseph M. Brandwein, Zbigniew M. Szczepiorkowski, James P. AuBuchon, Rebecca L. Barty, and Ker-Ai Lee
Department of Medicine, McMaster University, Hamilton, ON, Canada
Department of Statistics & Actuarial Science, University of Waterloo, Waterloo, ON, Canada
Canadian Blood Services, Ottawa, ON, Canada
Haukeland University Hospital, Bergen, Norway
Cedars-Sinai Medical Center, Los Angeles, CA, United States
University Health Network, Toronto, ON, Canada
Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States
* Corresponding author; email: heddlen{at}mcmaster.ca.
A non-inferiority study was performed comparing low-dose and standard-dose prophylactic platelet transfusions.
Methods: A double-blind RCT was performed in six sites in three countries. Thrombocytopenic adults requiring prophylactic platelet transfusion were randomly allocated to standard-dose (300 to 600 x 109 platelets/product) or low-dose platelets (150 to <300 x 109 platelets/product). The primary outcome (WHO bleeding 
Grade 2) was assessed daily through clinical examination, patient interview and chart review. A WHO grade was assigned through adjudication.
Results: The Data Safety Monitoring Board stopped the study because the difference in the Grade 4 bleeding reached the prespecified threshold of 5%. At this time, 129 patients had been randomized and 119 patients were included in the analysis (58 low dose; 61 standard dose). Three patients in the low-dose arm (5.2%) had Grade 4 bleeds compared to none in the standard-dose arm. WHO bleeding Grade 2 was 49.2% (30/61) in the standard dose arm and 51.7% (30/58) in the low dose group (RR 1.052; 95% CI 0.737, 1.502).
Conclusion: A higher rate of Grade 4 bleeding in patients receiving low-dose prophylactic platelet transfusions resulted in this RCT being stopped. Whether this finding was due to chance or represents a real difference requires further investigation. These clinical studies are registered on www.clinicaltrials.gov as NCT00420914.
