Recent advances in NICU platelet transfusions

Introduction

Thrombocytopenia (defined as a platelet count <150 × 10 ⁹ /L) is the second most common hematologic problem among neonates admitted to the neonatal intensive care unit (NICU), affecting 20% to 25% of this patient population. The incidence of thrombocytopenia increases with decreasing gestational age and birth weight, reaching ~70% among extremely low birth weight (ELBW) neonates (born with a weight <1000 g). The incidence of bleeding, particularly intracranial bleeding, is also highest among the most preterm neonates, with approximately 20% to 25% of neonates born at less than 1500 g developing an intraventricular hemorrhage (IVH) during the first week of life.

Consistent with the high frequency of thrombocytopenia and bleeding in this population, platelets are the second most common blood product (after red blood cells) transfused to NICU patients, with most platelet transfusions being given prophylactically to nonbleeding patients. However, the platelet count below which the bleeding risk increases to the point of justifying a transfusion was (until recently) unknown, and this led to substantial worldwide variability in platelet count thresholds used to transfuse NICU patients. This was first evident in survey studies conducted among North American neonatologists, in which the platelet transfusion thresholds selected ranged from less than 10 to less than 100 × 10 ⁹ /L in every one of the 15 clinical scenarios presented, with less than 50 × 10 ⁹ /L being the most commonly chosen threshold throughout. Interestingly, when the same survey was translated into German and sent to European neonatologists in German-speaking countries (Germany, Austria, and Switzerland), the most commonly selected transfusion threshold was lower (<25 × 10 ⁹ /L) in most clinical vignettes, although similar overall variability was observed. Statistical analysis comparing the transatlantic responses to the same survey suggested that North American neonatologists give 2.3-fold more platelet transfusions to NICU patients, based on practice variability alone. Subsequent observational multicenter studies conducted in the United States and Europe further supported this conclusion: In a recent study of neonatal transfusion practices in seven US hospitals from 2013 and 2016, the median platelet count prior to over 1000 platelet transfusions was 71 × 10 ⁹ /L for neonates in general, and it was greater than 45 × 10 ⁹ /L in all gestational and postnatal age groups examined. In an observational multicenter study from the United Kingdom, in contrast, the mean platelet count prior to transfusion was 27 × 10 ⁹ /L.

Platelet transfusions and prevention of bleeding