Abstract: Objective To evaluate the platelet transfusion threshold, demand, transfusion efficiency and engraftment kinetics of inpatients undergoing autologous hematopoietic stem cell transplantation（ASCT）, as well as the influence of different conditioning regimens on platelet transfusion. Methods This study was a single-center retrospective clinical study,and enrolled 94 patients who underwent ASCT and received platelet transfusions from November 2013 to March 2021 in the Department of Hematology,HuaShan Hospital affiliated to FuDan University. The influence of different conditioning regimens was compared on nucleated cell count,CD34⁺ stem cell dose,platelet transfusion threshold,total platelet transfusion dosage,transfusion efficiency and platelet engraftment kinetics. Results The mean value of nucleated cell and CD34⁺ stem cell reinfusion was（3.02±1.28）×10⁸/kg and（4.76±2.25）×10⁶/kg respectively,the average platelet transfusion per capita was 2.16 dose,the overall transfusion efficiency was 74.38%,and the median time of platelet engraftment was 12 days. Platelet transfusion dosage,effective transfusion rate,engraftment time and transfusion effect were similar between the groups of patients with platelet count below or over 10×10⁹/L. Patients was subgrouped into three groups with melphalan monotherapy,BuCy regimen,and CEC regimen,and there was no difference in blood type distribution,nucleated cell count,CD34⁺ stem cell dose and baseline platelets count among three groups. The data showed the amount of platelet transfusion in BuCy group was more than that of melphalan monotherapy group and CEC group（P<0.05）,the rate of platelet reduction in BuCy group was faster than that in melphalan monotherapy group and CEC group（P<0.05）, as well as the engraftment time was longer in BuCy group （P<0.05）. Conclusion In ASCT, on the basis of effective controlling complications and avoiding drug-related thrombocytopenia, the prophylactic platelet transfusion threshold can be triggered with 10×10⁹/L to reduce the risk of serious bleeding events. Compared with melphalan monotherapy and CEC regimen,BuCy regimen has a greater impact on the platelet reduction and engraftment time and patients require more platelet transfusions. However,due to the similar transfusion efficiency,there is no need to increase the platelet transfusion threshold.

Key words: Platelet transfusion, Autologous hematopoietic stem cell transplantation, Prophylactic transfusion conditioning regimen