ABO-Incompatible Platelet Transfusions and Mortality Risk in Patients With Intracranial Hemorrhage

Best platelet transfusion practices are unclear across intracranial hemorrhage (ICH) types, given the mortality risk. Reasons for this risk are unknown, but ABO-incompatible platelet transfusions may confer risk in certain populations. We assessed contemporary ICH platelet transfusion practices and whether ABO-incompatible platelet transfusions increase ICH mortality risk.

Adult patients with spontaneous intracerebral hemorrhage (sICH), traumatic ICH, and aneurysmal subarachnoid hemorrhage hospitalizations between 2019 and 2024 were assessed from a multicenter transfusion network. Relationships of platelet transfusions with 30-day mortality were assessed using logistic regression models adjusting for demographics, ICH type/severity, comorbidities, and other hemorrhage control therapies/transfusions. Among those receiving platelet transfusions, relationships of major ABO-incompatible platelet units with mortality risk were investigated using Cox models adjusting for similar covariates. Analyses were performed across the cohort and stratified by ICH subtype.

Among 13 068 patients with ICH, 60% were male individuals, mean age was 66 (±19) years, 23% were from sICH, 69% from traumatic ICH, and 8% from aneurysmal subarachnoid hemorrhage cohorts. Acute platelet transfusions were given to 12% of the patients. Thrombocytopenia (<100 000 platelets/μL) and neurosurgical procedures, seen in 6% and 18% of the patients, respectively, were largest factors for platelet transfusions. In regression analyses, platelet transfusions themselves did not associate with mortality (adjusted hazard ratio [HR]: 1.14 [0.96-1.35]). However, among patients with ICH receiving platelet transfusions, ABO-incompatible units were common (37%) and had dose-dependent relationships with mortality (adjusted HR ≥2 exposures: 1.78 [1.18-2.70]). Stratified analyses revealed that patients with sICH were particularly vulnerable to mortality from even single exposures of ABO-incompatible units (adjusted HR 1 exposure: 1.97 [1.13-3.45]; ≥2 exposures: 2.78 [0.98-7.87]) compared with other ICH subtypes.

Acute platelet transfusion practice remains prevalent in ICH, and platelet transfusion-related 30-day mortality risk may be influenced by ABO-incompatible platelet units. Clinical trials are needed to assess whether transfusion practice changes in providing ABO-matched platelets can improve outcomes in certain patients with ICH.