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

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.

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.

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).

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.