Neonatal Platelet Transfusions: Starting Again

Platelet transfusion in neonatal intensive care units of 22 European countries: a prospective observational study

Background

Platelet transfusions are given to preterm infants with severe thrombocytopenia aiming to prevent haemorrhage. The PlaNeT2/MATISSE trial revealed higher rates of mortality and/or major bleeding in preterm infants receiving prophylactic platelet transfusions at a platelet count threshold of 50 × 109/L compared to 25 × 109/L. The extent to which this evidence has been incorporated into clinical practice is unknown, thus we aimed to describe current neonatal platelet transfusion practices in Europe.

Methods

We performed a prospective observational study in 64 neonatal intensive care units across 22 European countries between September 2022 and August 2023. Outcome measures included observed transfusion prevalence rates (per country and overall, pooled using a random effects Poisson model), expected rates based on patient-mix (per country, estimated using logistic regression), cumulative incidence of receiving a transfusion by day 28 (with death and discharge considered as competing events), transfusion indications, volumes and infusion rates, platelet count triggers and increment, and adverse effects.

Findings

We included 1143 preterm infants, of whom 71 (6.2%, [71/1143]) collectively received 217 transfusions. Overall observed prevalence rate was 0.3 platelet transfusion days per 100 admission days. By day 28, 8.3% (95% CI: 5.5-11.1) of infants received a transfusion. Most transfusions were indicated for threshold (74.2%, [161/217]). Pre-transfusion platelet counts were above 25 × 109/L in 33.1% [53/160] of these transfusions. There was significant variability in volume and duration.

Interpretation

The restrictive threshold of 25 × 109/L is being integrated into clinical practice. Research is needed to explore existing variation and generate evidence for various aspects including optimal volumes and infusion rates.

Funding

Sanquin, EBA, and ESPR.

Lowering platelet-count threshold for transfusion in preterm neonates decreases the number of transfusions without increasing severe hemorrhage events

Thrombocytopenia is common in preterm neonates and can be associated with hemorrhage. Most platelet transfusions are prophylactic. Previously, higher platelet-count thresholds were recommended for neonates, but this recommendation has been questioned in recent studies. In the PlaNeT2 trial, mortality and serious bleeding were more frequent in neonates with the highest platelet-count threshold than in others. Following this trial, we changed our platelet transfusion practice by lowering the platelet-count threshold for prophylactic transfusion from 50,000 to 25,000/mm3. We conducted a before-after retrospective cohort study to quantify the frequency of platelet transfusions and assess the new protocol by analyzing death and serious hemorrhage events. This retrospective monocentric study included neonates born before 37 weeks of gestation with platelet count < 150,000/mm3 during the 2 years preceding the new platelet transfusion protocol (high prophylactic transfusion threshold, 50,000/mm3) and during the 2 years after the new platelet transfusion protocol (low prophylactic transfusion threshold, 25,000/mm3). The primary outcome was the proportion of neonates receiving at least one platelet transfusion in both groups. We also compared the proportion of deaths and severe hemorrhage events. A total of 707 neonates with thrombocytopenia were identified. In the high-threshold group, 99/360 (27.5%) received at least one platelet transfusion as compared with 56/347 (16.1%) in the low-threshold group (p < 0.001). The groups did not differ in proportion of deaths or severe hemorrhage events.

CONCLUSIONS

A reduced platelet-count threshold for transfusion allowed for a significant reduction in the number of platelet transfusions without increasing severe hemorrhage events.

WHAT IS KNOWN

• A recent randomized trial suggested that restrictive platelet-count thresholds for platelet transfusion could be beneficial for preterm neonates.

WHAT IS NEW

• On lowering the platelet-count threshold for transfusion from 50,000 to 25,000/mm3, the number of transfusions significantly decreased without increasing severe hemorrhage events in a neonatal intensive care unit.

Neonatal Intensive Care Unit Patients Receiving More Than 25 Platelet Transfusions

OBJECTIVE

A few patients in neonatal intensive care units (NICU) receive numerous platelet transfusions. These patients can become refractory, defined as transfusions of ≥10 mL/kg failing to increase the platelet count by at least 5,000/µL. Causes of, and best treatments for, platelet transfusion refractoriness in neonates have not been defined.

STUDY DESIGN

Multi-NICU multiyear retrospective analysis of neonates receiving >25 platelet transfusions.

RESULTS

Eight neonates received 29 to 52 platelet transfusions. All eight were blood group O. Five had sepsis, four were very small for gestational age, four had bowel resections, two Noonan syndrome, two had cytomegalovirus infection. All eight had some (19-73%) refractory transfusions. Many (2-69%) of the transfusions were ordered when the platelet count was >50,000/µL. Higher posttransfusion counts occurred after ABO-identical transfusions (p = 0.026). Three of the eight had late NICU deaths related to respiratory failure; all five survivors had severe bronchopulmonary dysplasia requiring tracheostomy for prolonged ventilator management.

CONCLUSION

Neonates who are high users of platelet transfusions appear to be at high risk for poor outcomes, especially respiratory failure. Future studies will examine whether group O neonates are more likely to develop refractoriness and whether certain neonates would have a higher magnitude of posttransfusion rise if they received ABO-identical donor platelets.

KEY POINTS

· Many of the platelet transfusions given in the NICU are given to a small subset of patients.. · Refractoriness to platelet transfusions is common among these very high recipients.. · Neonates who are high users of platelet transfusions appear to be at high risk for poor outcomes..

Platelet transfusions in preterm infants: current concepts and controversies-a systematic review and meta-analysis

Platelet transfusions (PTx) are the principal approach for treating neonatal thrombocytopenia, a common hematological abnormality affecting neonates, particularly preterm infants. However, evidence about the outcomes associated with PTx and whether they provide clinical benefit or harm is lacking. The aim of this systematic review and meta-analysis is to assess the association between PTx in preterm infants and mortality, major bleeding, sepsis, and necrotizing enterocolitis (NEC) in comparison to not transfusing or using different platelet count thresholds for transfusion. A broad electronic search in three databases was performed in December 2022. We included randomized controlled trials, and cohort and case control studies of preterm infants with thrombocytopenia that (i) compared treatment with platelet transfusion vs. no platelet transfusion, (ii) assessed the platelet count threshold for PTx, or (iii) compared single to multiple PTx. We conducted a meta-analysis to assess the association between PTx and mortality, intraventricular hemorrhage (IVH), sepsis, and NEC and, in the presence of substantial heterogeneity, leave-one-out sensitivity analysis was performed. We screened 625 abstracts and 50 full texts and identified 18 reports of 13 eligible studies. The qualitative analysis of the included studies revealed controversial results as several studies showed an association between PTx in preterm infants and a higher risk of mortality, major bleeding, sepsis, and NEC, while others did not present a significant relationship. The meta-analysis results suggest a significant association between PTx and mortality (RR 2.4, 95% CI 1.8-3.4; p < 0.0001), as well as sepsis (RR 4.5, 95% CI 3.7-5.6; p < 0.0001), after a leave-one-out sensitivity analysis. There was also found a significant correlation between PTx and NEC (RR 5.2, 95% CI 3.3-8.3; p < 0.0001). As we were not able to reduce heterogeneity in the assessment of the relationship between PTx and IVH, no conclusion could be taken.    Conclusion: Platelet transfusions in preterm infants are associated to a higher risk of death, sepsis, and NEC and, possibly, to a higher incidence of IVH. Further studies are needed to confirm these associations, namely between PTx and IVH, and to define the threshold from which PTx should be given with less harm effect. What is Known: • Platelet transfusions are given to preterm infants with thrombocytopenia either to treat bleeding or to prevent hemorrhage. • Lack of consensual criteria for transfusion. What is New: • A significant association between platelet transfusions and mortality, sepsis, and NEC.

The Usability of Platelet Mass Index Thresholds to Assess the Repeated Platelet Transfusion Requirements in Neonates

To evaluate the usability of platelet mass index (PMI) thresholds to assess the repeated platelet transfusion requirements in neonates who have received transfusion within the previous six days. This is a retrospective cross-sectional study conducted with neonates who received prophylactic platelet transfusion. The PMI was calculated as platelet count (× 1000/mm3) × mean platelet volume (MPV) (fL). Platelet transfusions were divided into two groups as first (Group 1) and repeated transfusions (Group 2). The increment and percentage of increment in platelet counts, MPV and PMI after transfusion were compared between the two groups. The amounts of changes were calculated as: (Post-transfusion) - (Pre-transfusion values). The percentages of changes were calculated as: ([Post-transfusion - Pre-transfusion values]/Pre-tansfusion values) × 100. Eighty three platelet transfusions were analyzed in 28 neonates. The median gestational age and birth weight were 34.5 (26-37) weeks, and 2225 (752.5-2937.5) grams, respectively. There were 20 (24.1%) transfusions in Group 1, and 63 (75.9%) transfusions in Group 2. There were no differences in the amounts of changes in platelet counts, MPV and PMI between the groups (p > 0.05). When the percentages of changes were analyzed, it was found that the platelet counts and PMI in Group 1 increased to a greater extent compared to Group 2 (p = 0.026, p = 0.039, respectively), but no significant difference was found in MPV between the groups (p = 0.081). The lower percentage of change in PMI in Group 2 was associated with the lower percentage of change in platelet counts. Being transfused with adult platelets did not affect platelet volume of the neonates. Therefore, PMI thresholds can be used in neonates with a history of platelet transfusion.

Platelet Transfusions in a Multi-NICU Healthcare Organization Before And After Publication of the PlaNeT-2 Clinical Trial

OBJECTIVES

To evaluate whether implementing more restrictive NICU platelet transfusion guidelines following the PlaNeT-2 randomized controlled trial (transfusion threshold changed from 50,000/μL to 25,000/μL for most neonates) was associated with fewer NICU patients receiving a platelet transfusion, without adversely affecting outcomes.

STUDY DESIGN

Multi-NICU retrospective analysis of platelet transfusions, patient characteristics, and outcomes during three years before vs. three years after revising system-wide guidelines.

RESULTS

During the first period, 130 neonates received one or more platelet transfusions; this fell to 106 during the second. The transfusion rate was 15.9/1000 NICU admissions in the first period vs. 12.9 in the second (p=0.106). During the second period, a smaller proportion of transfusions was administered when the platelet count was in the 50,000 - 100,000/μL range (p=0.017), and a larger proportion when it was <25,000/μL (p=0.083). We also saw a fall in the platelet counts that preceded the order for transfusion from 43,100/μL to 38,000/μL (p=0.044). The incidence of adverse outcomes did not change.

CONCLUSIONS

Changing platelet transfusion guidelines in a multi-NICU network to a more restrictive practice was not associated with a significant reduction in number of neonates receiving a platelet transfusion. The guideline implementation was associated with a reduction in the mean platelet count triggering a transfusion. We speculate that further reductions in platelet transfusions can safely occur with additional education and accountability tracking.

How I use platelet transfusions

Platelet transfusions are commonly administered for the prevention or treatment of bleeding in patients with acquired thrombocytopenia across a range of clinical contexts. Recent data, including randomized trials, have highlighted uncertainties in the risk-benefit balance of this therapy, which is the subject of this review. Hemovigilance systems report that platelets are the most frequently implicated component in transfusion reactions. There is considerable variation in platelet count increment after platelet transfusion, and limited evidence of efficacy for clinical outcomes, including prevention of bleeding. Bleeding events commonly occur despite the different policies for platelet transfusion prophylaxis. The underlying mechanisms of harm reported in randomized trials may be related to the role of platelets beyond hemostasis, including mediating inflammation. Research supports the implementation of a restrictive platelet transfusion policy. Research is needed to better understand the impact of platelet donation characteristics on outcomes, and to determine the optimal thresholds for platelet transfusion before invasive procedures or major surgery (eg, laparotomy). Platelet transfusion policies should move toward a risk-adapted approach that does not focus solely on platelet count.

Cerebral vasculature exhibits dose-dependent sensitivity to thrombocytopenia that is limited to fetal/neonatal life

Whether increasing platelet counts in fetal and neonatal alloimmune thrombocytopenia (FNAIT) is effective at preventing intra-cerebral hemorrhage (ICH) has been a subject of debate. The crux has been whether thrombocytopenia is the major driver of ICH in diseases such as FNAIT. We recently demonstrated in mice that severe thrombocytopenia was sufficient to drive intra-cerebral hemorrhage in utero and in early neonatal life. It remains unclear what degree of thrombocytopenia is required to drive ICH and for how long after birth thrombocytopenia can cause ICH. By inducing a thrombocytopenic range, we demonstrate that there is a large buffer-zone of mild thrombocytopenia that does not result in ICH, that ICH becomes probabilistic at 40% of normal platelet numbers, and that ICH becomes fully penetrant below 10% of normal platelet number. We also demonstrate that although the neonatal mouse is susceptible to thrombocytopenia-induced ICH, this sensitivity is rapidly lost between post-natal days 7 - 14. These findings provide important insights into the risk of in utero ICH with varying degrees of thrombocytopenia and into defining the developmental high-risk period for thrombocytopenia-driven ICH in a mouse model of FNAIT.

Individualized Bleeding Risk Assessment through Thromboelastography: A Case Report of May-Hegglin Anomaly in Preterm Twin Neonates

May–Hegglin anomaly (MHA) is a rare autosomal dominant disorder in the spectrum of myosin heavy chain-related disorders (MYH9-RD), characterized by congenital macrothrombocytopenia and white blood cell inclusions. MHA carries a potential risk of hemorrhagic complications. Bleeding diathesis is usually mild, but sporadic, life-threatening events have been reported. Data regarding the clinical course and outcomes of neonatal MYH9-RD are limited, and specific guidelines on platelet transfusion in asymptomatic patients are lacking. We present monochorionic twins born preterm at 32 weeks of gestation to an MHA mother; both presented with severe thrombocytopenia at birth. Peripheral blood smear demonstrated the presence of macrothrombocytes, and immunofluorescence confirmed the diagnosis of MHA. Close clinical monitoring excluded bleeding complications, and serial hemostatic assessments through a viscoelastic system demonstrated functionally normal primary hemostasis in both patients. Therefore, prophylactic platelet transfusions were avoided. Whole DNA sequencing confirmed the pathogenetic variant of MHA of maternal origin in both twins. Thromboelastography allowed real-time bedside bleeding risk assessment and supported individualized transfusion management in preterm newborns at risk of hemostatic impairment. This report suggests that dynamic and appropriate clotting monitoring may contribute to the more rational use of platelets’ transfusions while preserving patients with hemorrhagic complications and potential transfusion-related side effects.