One-unit compared to two-unit platelet transfusions for adult oncology outpatients

Background and Objectives: Platelet dosing has been studied in adult oncology inpatients, but there is almost no published evidence to guide platelet dosing for adult outpatients. We evaluated transfusion indices after 1 unit and 2 unit apheresis platelet transfusions at our hospital to determine whether a benefit to 2-unit transfusions could be detected. Materials and Methods: A retrospective chart review was conducted of all adult oncology patients who received an outpatient platelet transfusion over a 16-month period (July 2016–November 2017). Pre- and post-transfusion platelet count, and chronology of subsequent platelet transfusions were compared. Results: A total of 8467 platelet transfusions were administered to 602 patients during the study period. 59·8% of patients (n = 360) were transfused interchangeably with one or two platelets throughout the study period. The primary study population were comprised of these patients. On average, a 2-unit platelet transfusions resulted in a higher immediate post-transfusion platelet count (43 vs. 37 x 10³/μl, P < 0·001) and a lower corrected count increment (9707 vs. 14 060, P < 0·001). Transfusion with 2 platelets did not increase the number of days between outpatient transfusions (median; 4 vs. 4, P = 0·959) or the platelet count at the time of next transfusion (11 vs. 11 x 10³/μl, P = 0·147). Conclusion: Among adult, oncology outpatients that were transfused interchangeably with one or two units of platelets, transfusion with two platelets did not offer a durable improvement in platelet count or impact the subsequent transfusion schedule.