Procedure for including patients in trial of transfusing platelets in patients with hematologic thrombocytopenia. Randomized patients had no clinical or biologic features that would impair platelet transfusion efficiency. For the final analysis, 5 patients never receiving a transfusion after randomization were excluded. (AL indicates acute leukemia undergoing first-line treatment; AT, undergoing autologous hematopoietic stem cell transplantation.