This study, the first large-scale clinical trial to compare the effects of different platelet-transfusion dosing regimens on hemostatic outcomes in patients with hypoproliferative thrombocytopenia, found that patients can be safely and effectively transfused with a low dose of platelets, a strategy that can reduce costs and help prevent shortages in the blood supply.

A total of 1,272 patients with hypoproliferative thrombocytopenia ( which is caused by failure of the marrow to produce platelets ) who were expected to be hospitalized with platelet counts of less than or equal to 10,000 microliters for more than five days were enrolled in the study and received at least one platelet transfusion. Patients were randomized to receive one of three platelet-transfusion dosing regimens: a low dose ( 1.1 x 1011 platelets/m2 ), a medium dose [ 2.2 x 10(11) platelets/m2 ], or a high dose [ 4.4 x 10(11) platelets/m2 ]. An acceptable dose of platelets could be within 25 percent ( lower or higher ) of the target dose. Patients were stratified into four groups based on the cause of thrombocytopenia: those who had received chemotherapy for a hematologic malignancy ( 313 patients ), chemotherapy for a solid tumor ( 7 patients ), autologous stem cell transplant (429 patients), or an allogeneic stem cell transplant ( 523 patients ). Patients were prophylactically transfused on days when platelet counts were less than or equal to 10,000 microliters.

The primary endpoint of the study was the percentage of patients with Grade 2 or higher bleeding, calculated using the WHO Bleeding Scale. Grade 2 bleeding is clinically significant bleeding that does not require a red blood cell transfusion. Grade 2 or higher bleeding occurred in 71 percent of patients in the low-dose arm, 69 percent in the medium-dose arm, and 70 percent in the high-dose arm. Grade 3 or higher bleeding, which generally does require treatment by red blood cell transfusion, was seen in 12 percent of patients in the low-dose arm, 9 percent in the medium-dose arm, and 10 percent in the high-dose arm. Grade 4 bleeding, the most serious, was seen in 3 percent, 2 percent, and 2 percent of patients in the low-dose, medium-dose, and high-dose arms, respectively. The median number of red blood cell transfusions ( usually given for anemia ) was four in each treatment arm. Treatment dose did not affect the frequency of any bleeding grade in any of the four patient groups.

Source: American Society of Hematology, 2008

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