P1585: platelet transfusion increment in the setting of hematopoietic stem cell transplantation patients: a single-center prospective study

Topic: 31. Transfusion medicine Background: Platelet transfusions (PT) are a standard supportive therapy for thrombocytopenic patients undergoing chemotherapy or hematopoietic stem cell transplantion (HSCT), either with a prophylactic or a curative purpose. Aims: Due to the increasing cost of apheresis platelets, we aimed to evaluate the efficiency of whole blood–derived platelet concentrates (PC) in HSCT patients. Methods: We conducted a descriptive prospective study in the National Bone Marrow Transplant Center of Tunis in collaboration with the National Blood Transfusion Center, between March and June 2022. All PT administered to hospitalized patients were evaluated, except those performed urgently or in the weekends, for lack of quality control. Pools of 8 PC were prepared for adult patients and 1 PC/ 10Kg of weight for pediatric ones. After transformation, a 5mL sample was collected using a sterile connection to an auxiliary bag, in order to calculate the absolute number of platelets in the pool. A CBC count was performed 1 hour and 24 hours after PT to calculate the corrected count increment (CCI). The PT efficiency was evaluated by the resolution (curative PT) or the non-occurrence of bleeding (prophylactic PT), the CCI and time to next transfusion. Results: Thirty five patients were included (autologous HSCT n=12, allogenic HSCT n=23) receiving a total of 108 whole blood–derived PT (prophylactic PT n= 90, curative PT n=12, before invasive act n=6). Patients’ median age was 35 years old (7-64) with a gender-ratio of 1.2. The underlying disease was acute leukemia (n=17), aplastic anemia (n=6), lymphoma (n=6) and multiple myeloma (n=6). Factors influencing PT efficiency were evaluated: splenomegaly (n=1), sinusoidal occlusion syndrome (SOS) (n=4), thrombotic microangiopathy (n=1), HLA immunisation (n=4), ongoing infection (n=42) and drugs (n=4). The median age of PC was 3 days (2-5). The median pool volume was 401 mL (152 - 610) with a median platelet count of 1.53 x 1011 (0.17-3.75). Only 28% of pools had a platelet count over 2 x 1011. ABO compatibility was respected for all but 2 PT. Five out of the 12 curative PT resulted in the resolving of the bleeding and only one patient presented a bleeding following a prophylactic PT. Time to next transfusion was 24, 48 and 72 hours or more in 79%, 7% and 6% of the cases respectively. The 8% remaining PT were punctual, concomitant with platelet recovery. The median CCI at H1 was 7.98 (-20 – 59) and 4.36 (-42 – 59) at H24. Thus, 40% and 63% of pool transfusions were considered inefficient at H1 and H24 respectively. Of all factors supposedly affecting the transfusion efficiency, anti HLA immunization stood out as an independent factor in multivariate analysis with p of 0.04. Despite the clinical efficacy of PT, a low CCI was noted in the majority of cases. This is in part due to the relatively low platelet count in the pool making the enhancement of quality control an urgent matter. Conclusion: In view of our results, corrective measures are necessary. Optimization of the richness of the platelet pools must be made a priority. Keywords: Allogeneic stem cell transplant, Autologous hematopoietic stem cell transplantation, Anti-platelet antibody, Platelet transfusion