The relationship between clinical features of blood donors and health outcomes among recipients remains unclear, according to a study recently published in Transfusion and Apheresis Science.
Millions of individuals in the United States require blood transfusions each year. In many diseases, such as fetal and neonatal alloimmune thrombocytopenia (FNAIT), platelet transfusions may be life-saving.
Several studies, the majority of which are observational, have attempted to uncover the associations between donor sex, age, history of pregnancy, smoking status and more on the health outcomes of recipients.
“Results of these studies are inconsistent, thus highlighting the need
for well-designed studies to further investigate the complex relationships between donor, component, and recipient factors–and how these impact patient outcomes,” the authors explain. In their literature review, Ning et al. summarize the existing data and discuss discrepancies that remain.
Read more about FNAIT treatment and care
Donor characteristics
Overall, studies have found that the quality of different components of blood can vary with age. For example, older donors tend to have reduced hemoglobin levels and red blood cell counts, as well as worsened platelet survival.
However, the effect of age on long- and short-term patient outcomes remains unclear. While some studies found that red blood cell transfusions from younger donors were associated with slightly higher mortality rates than transfusions from older donors, other studies have found no such association. Some suggest that transfusions from younger donors have a protective effect.
Like donor age, the impact of donor sex on patients outcomes remains inconclusive. However, transfusion-related acute lung injury has consistently been associated with the receipt of blood from an individual with a history of pregnancy.
Studies have also analyzed whether sex-matching donors and recipients impacts outcomes. While some have found no association, a Dutch study found that male patients who received red blood cell transfusions from male donors had improved survival 6 months post-transfusion. A 2019 analysis concluded that when transfusions are sex-mismatched, there is a higher risk of mortality among recipients.
The first randomized control trial evaluating the impact of donor sex on outcomes was published in 2023. Results found no significant difference in mortality between those who received blood from a male donor and those who received blood from a female donor.
Although this review does not include data on individuals with FNAIT, the researchers also examined studies of infants receiving transfusions. Again, while some studies found no associations between the sex or age of donors and morbidity and mortality among neonates, others show that infants who receive transfusions from older females have improved outcomes.
The authors mention a variety of other factors as well, including obesity, smoking and presence of chronic diseases. Results are similarly inconclusive.
Ning et al. conclude by calling for further research into these relationships, potentially through the use of machine learning and data mining. They also emphasize the need for more studies including groups that are currently underrepresented in transfusion studies, including infants, women, older adults and Hispanic individuals .
