Effects of ABO matching of platelet transfusions in critically III children

Objectives: To determine if transfusing ABO compatible platelets has a greater effect on incremental change in platelet count as compared to ABO incompatible platelets in critically ill children. Design: Secondary analysis of a prospective, observational study. Transfusions were classified as either ABO compatible, major incompatibility, or minor incompatibility. The primary outcome was the incremental change in platelet count. Transfusion reactions were analyzed as a secondary outcome. Setting: Eighty-two PICUs in 16 countries. Patients: Children (3 d to 16 yr old) were enrolled if they received a platelet transfusion during one of the predefined screening weeks. Interventions: None. Measurements and Main Results: Five-hundred three children were enrolled and had complete ABO information for both donor and recipient, as well as laboratory data. Three-hundred forty-two (68%) received ABO-identical platelets, 133 (26%) received platelets with major incompatibility, and 28 (6%) received platelets with minor incompatibility. Age, weight, proportion with mechanical ventilation or underlying oncologic diagnosis did not differ between the groups. After adjustment for transfusion dose, there was no difference in the incremental change in platelet count between the groups; the median (interquartile range) change for ABO-identical transfusions was 28 × 10⁹ cells/L (8-68 × 10⁹ cells/L), for transfusions with major incompatibility 26 × 10⁹ cells/L (7-74 × 10⁹ cells/L), and for transfusions with minor incompatibility 54 × 10⁹ cells/L (14-81 × 10⁹ cells/L) (p = 0.37). No differences in count increment between the groups were noted for bleeding (p = 0.92) and nonbleeding patients (p = 0.29). There were also no differences observed between the groups for any transfusion reaction (p = 0.07). Conclusions: No differences were seen in the incremental change in platelet count nor in transfusion reactions when comparing major ABO incompatible platelet transfusions with ABO compatible transfusions in a large study of critically ill children. Studies in larger, prospectively enrolled cohorts should be performed to validate whether ABO matching for platelet transfusions in critically ill children is necessary.