Does sex matter in red blood cell transfusions?

When doctors select red blood cell units for transfusion into a patient, they consider the patient’s blood type to determine what types of donor blood would be compatible. What they don’t consider is the sex of the patient and whether the donor is the same (sex-matched) or different sex (sex-mismatched). But this may be a factor worth considering, according to a study led by Dr. Michelle Zeller, Canadian Blood Services medical officer and assistant professor in the department of medicine at McMaster University. 

The study, “Sex-mismatched red blood cell transfusions and mortality: A systematic review and meta-analysis,” was published in May this year in Vox Sanguinis, a peer-reviewed medical journal covering hematology — the study of the physiology of blood.   

Dr. Zeller’s team summarized the evidence from studies that compared outcomes in patients who received sex-matched or sex-mismatched red blood cell transfusions. Their analysis suggests that sex-mismatched red blood cell transfusions may be associated with a higher risk of death, but more investigation is needed.  

Dr. Zeller notes that the findings need to be interpreted with caution because the quality of the evidence from the studies they analysed was very low. “Although our study looked at the outcomes of over 85,000 patients, we found only observational studies — which have a higher risk of bias — available for our analysis,” she says. “But the findings suggest sex-mismatching in red blood cell transfusion is a potentially important issue that needs to be more rigorously examined.” 

• To learn more about the study, read our latest Research Unit

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The opinions reflected in this post are those of the author and do not necessarily reflect the opinions of Canadian Blood Services nor do they reflect the views of Health Canada or any other funding agency.