Impact of Clinical Factors on Platelet Engraftments In Contemporary Stem Cell Transplantation.

Abstract Abstract 4522 Background: Conditioning regimens utilized to prepare patients for stem cell transplantation uniformly result in suppression of marrow function, leading to prolonged recovery of neutrophils and platelets. Neutropenia increases the risk of infection while thrombocytopenia and prolonged platelet engraftment time can result in increased risk of bleeding as well as morbidities associated with subsequent transfusions. The variations in duration of cytopenias are affected by multiple factors including regimen intensity and other clinical factors. Methods: In this retrospective study of consecutive patients undergoing stem cell transplantation at the University of Rochester between 2005 and 2009 for radiation—containing regimens, and between 2007 and 2009 for non-radiation containing regimens, we assessed the relationship between platelet engraftment times and source of stem cells, type of graft, and the effect of conditioning regimen intensity. Platelet engraftment was defined per standard CIBMTR definitions – platelet engraftment occurred at the first of 3 days of platelet count >20,000/μ L without platelet transfusions for 7 days, and/or the first day of platelet count >100,000/μ L. Guidelines for transfusion support stipulated a 10,000/μ L threshold for platelets in the absence of bleeding and a hemoglobin of 8.0 g/dL for red cells in the absence of other symptoms. The time to platelet engraftment and the number of platelet transfusions required prior to engraftment were analyzed in those patients with platelet nadir Results: The 25th percentile, median and 75th percentile (days) for the time to platelet engraftment in days, calculated using the method of cumulative incidence for the non-TBI and TBI containing conditioning regimens, are shown below: Conditioning regimen Time to platelet engraftment (days) 25th percentile 50th percentile (median) 75th percentile With TBI 16 18 26 Without TBI 15 17 18 With conditioning regimens containing TBI or with chemotherapy alone (non-TBI), both donor type (auto, allo, or matched unrelated donor) and graft type (marrow, PBSCs, or umbilical cord blood) had significant effects on platelet engraftment time, with the longest engraftment times occurring in cord blood transplants. With both TBI and non-TBI conditioning regimens, donor and graft type significantly affected platelet transfusion numbers (p With non-TBI conditioning regimens, gender did not affect the number of platelet transfusions, but females received significantly more red cell transfusions up to 100 days post-transplant (p=0.003). Conclusions: These data indicate that times to platelet engraftment in stem cell transplant patients in the era of PBSC and reduced-intensity transplant regimens remains longer than two weeks in cases where conditioning regimens result in platelet nadir. This is associated with considerable utilization of transfusion resources. The increased need of RBC and platelet transfusions in females receiving TBI containing regimens and red cells in non-TBI conditioning cases despite similarity in platelet engraftment times is of interest, and underlying causes remain undetermined. Disclosures: No relevant conflicts of interest to declare.