Acetylsalicylic Acid During Leukapheresis Reduces the Incidence of Clotting in Hematopoietic Progenitor Cell Products

INTRODUCTION: Clots may be seen during hematopoietic progenitor cell (HPC) collection or on product arrival to the cell therapy processing laboratory. We have always given one 81 mg acetylsalicylic acid (ASA) when clotting is seen during collection if there is no allergy, but hypothesized that the incidence of clotting would decrease if ASA was given to all autologous collectors with a platelet count of ≥80×109/L prior to collection (pre-emptively). METHODS: Autologous HPC were collected using the Spectra Optia instrument or Cobe Spectra instrument (Terumo BCT®, Lakewood, CO) with heparinized citrate. A retrospective review was performed to determine the total number of HPC products, including products with clots, collected between September 2010 and August 2013 (group 1). All autologous HPC collectors from September 2013 onwards were given ASA pre-emptively if their platelet count was ≥80×109/L (group 2), and a similar review was performed in this group. We included the cell density and platelet count of the HPC products and the platelet count of the patient in the data collected. We reviewed procedure notes for adverse events or bleeding. RESULTS: A total of 2574 HPC products were collected between September 2010 and August 2013; clotting was observed in 66 HPC products (66/2574; 2.56%). A total of 1906 HPC products were collected between November 2013 and October 2016; clotting was observed in 24 HPC products (24/1906; 1.25%). Thus an overall reduction was seen in incidence of clotting between groups 1 and 2 (2.56% versus 1.25; P=0.002). Since not all collectors in group 2 received pre-emptive ASA, we reviewed the incidence of clotting within this group. A decrease in incidence of clots was noted with preemptive ASA (group 2A) (5/512, 0.97%) versus no ASA (group 2B) (19/1394, 1.36%), but this was not statistically significant. The mean cell density of the HPC products did not differ significantly between these two groups (group 2A and 2B) but a higher platelet count was observed in the pre-emptive ASA group as expected (group 2A) (P=0.004). Multivariate logistic analysis after adjusting for platelet count of the HPC products showed a trend towards reduced incidence of clotting in the pre-emptive ASA group (group 2A); however no association was seen after adjusting for the cell density of HPC products, nor was an association between patient's platelet count and incidence of clotting seen. None of the collectors who received ASA suffered any adverse events, including bleeding. CONCLUSION: We observed an overall reduction in the incidence of clotting in our HPC products after initiating pre-emptive ASA usage (2.56% versus 1.25%; P=0.002). A trend towards lower incidence of clotting was noted when further analysis was performed to include pre-emptive ASA usage and platelet count of the HPC products. Although the overall incidence of clotting was very small (<3.0%), giving ASA pre-emptively further reduced the incidence of clotting and thus prevented wastage/cell loss of HPC products.