Vein-to-Vein Study Identifies Donor Factors that Improve Platelet Function in Transfusions

Researchers have identified several donor and processing factors that may impact platelet function following transfusion, based on data from a large vein-to-vein database. Transfusion of platelets from donors with increasing BMI and high levels of SARS-CoV-2 nucleocapsid antibodies (anti-N Ab) were associated with higher odds of a recipient achieving a platelet increase of more than 20×10⁹/L (a co-primary endpoint), according to results of a new study published in Blood Advances.

The researchers found that for each 10-unit increase in donor BMI, there was an associated increased odds of a platelet increase 20×10⁹/L (multivariable adjusted odd ratio [aOR] = 1.16). Platelet units from donors with higher anti-N antibody levels were associated with platelet count increases than units from antibody-negative donors (aOR = 1.78).

“Obesity is an inflammatory condition associated with a prothrombotic state and thrombosis… SARS-CoV-2 infection causes a proinflammatory state that is associated with acute and longer-term thrombotic events in patients with COVID-19,” the researchers noted, explaining possible mechanisms.

In contrast, pathogen reduction, storage in platelet additive solution (PAS), and longer storage (5-7 days vs. less than 5 days [aOR = 0.77]) were associated with reduced odds of achieving platelet increases larger than 20×10⁹/L. Pathogen reduction without storage in PAS (aOR = 0.32) and storage in PAS without pathogen reduction (aOR = 0.24) were both significantly associated with reduced odds of platelet increases of more than 20×10⁹/L.

The researchers also examined RBC transfusion events 24 hours after platelet transfusion (a co-primary endpoint), which occurred in 37.7% of overall transfusion events. Increasing donor BMI (per 10-unit increase) was associated with lower odds of a 24-hour RBC transfusion event (aOR = 0.86). The researchers noted that “this finding was primarily evident in the subgroup of donors with obesity” (aOR = 0.82). Platelet units from donors with high anti-N antibody levels were associated with fewer 24-hour RBC transfusions than units from antibody-negative donors (aOR = 0.66). No difference was seen with platelets from vaccinated but uninfected donors (aOR = 0.92).

Pathogen reduction and irradiation were associated with increased odds of 24-hour RBC transfusion events — aOR 1= 0.31 and 1.24, respectively. In contrast, prolonged storage (5-7 days), storage in PAS, and platelet splits were not associated with differences in 24-hour RBC transfusion events.

For the study, the researchers identified 2,808 adults who received 8,207 single-unit platelet transfusions with donor SARS-CoV-2 serology data from Kaiser Permanente Northern California (KPNC). The American Red Cross (ARC) and Vitalant, which supply blood products to all 21 KPNC medical centers, collected information on blood donors, donations and product processing. This vein-to-vein approach allowed researchers to match donor characteristics and processing conditions with recipient outcomes.

Data was collected for each unit regarding blood donor demographics — including age, sex, BMI and ABO/Rh status — collection date, platelet processing characteristics (including the number of platelet splits, use of pathogen reduction, storage in PAS, storage duration and irradiation). SARS-CoV-2 screening was performed by ARC and Vitalant of all blood donations from June 2020 to June 2021. After that time, screening was performed as part of the Centers for Disease Control–funded Nationwide Blood Donor Serosurveillance study.

Collected recipient details included age, sex and BMI, along with platelet unit issue date of all adult KPNC inpatients and outpatients, who received a single unit of platelets during at least one transfusion episode at 21 medical centers from June 2020 to March 2022. Platelet counts were available before and after each transfusion event. Information was also collected on timing and number of transfused RBC products in the 24 hours before and after each platelet transfusion event.

Patients were aged 52 years on average, with a median BMI 29 kg/m²; 37.1% of platelet units came from female donors. The mean recipient was aged 64 years, and more than half (59.0%) were male; the median number of platelet transfusion episodes per recipient was three.

In terms of processing, the median number of platelet splits was two; median storage was 4 days, and 4.7% of platelet units were stored for more than 5 days. Only 16.6% of platelet units were irradiated. More than half of platelet units were pathogen reduced (55.7%) or stored in PAS (56.4%), with 87% pathogen-reduced platelets were stored in PAS.

“The strength of this study lies in its use of a large vein-to-vein data set that allows data to be tracked from blood donor to blood product to transfusion recipient. This represents an excellent resource enabling the discovery of associations that may have subtle yet important impacts on improving blood transfusion outcomes,” Nicole Relke, MD; Richard J. Cook, PhD; and Donald M. Arnold, MD, wrote in an accompanying commentary.