In this multicentre trial, infants born at less than 34 weeks of gestation and in whom severe thrombocytopenia was detected were randomised to receive a platelet transfusion at a platelet count threshold of 50 000/µL (high-threshold group) versus a threshold of 25 000/µL (low-threshold group). Preterm infants became eligible for randomisation provided there was no further major bleeding.
After randomisation, infants were assigned to receive platelet transfusion at a dose of 15 mL/kg. The authors report bleeding using a validated bleeding assessment tool (grading of bleeding as minor, moderate, major or severe) as well as a composite outcome of death or new major bleeding within 28 days after randomisation.
A total of 660 infants (median birth weight, 740 g; median gestational age, 26.6 weeks) underwent randomisation. A new major bleeding episode or death occurred in 26% of the infants (85 of 324) in the high-threshold group and in 19% (61 of 329) in the low-threshold group (odds ratio, 1.57; 95% confidence interval [CI], 1.06 to 2.32; P = 0.02).
The results of this trial are adding another piece of evidence that prophylactic platelet transfusion in this highly vulnerable patient group may increase mortality if a platelet count threshold of <50 000/µL is used, as compared to a lower threshold of 25 000/µL. Although this finding is suggested by already published retrospective studies, it is now supported by a large randomised controlled trial. The authors speculate that the reason for the between-group differences may be the occurrence of inflammatory consequences after transfusion, haemodynamic shifts due to platelet transfusion volume, or vessel occlusion by microthrombi. These results and the concept of lower thresholds for platelet transfusion in infants will hopefully trigger further investigations. It would be interesting to see if these data are reproducible in older children too. – Thorsten Haas