Photo by Elise Amendola
There is no association between sex-discordant blood transfusions and the risk of death after cardiac surgery, according to research published in Circulation.
Two previous studies suggested that patients who received red blood cells (RBCs) from a donor of the opposite sex had an increased risk of death after cardiac surgery.
However, the current study showed no significant difference between same-sex and opposite-sex donor-recipient pairs.
The researchers said the reason for the difference between the new and older studies is that, in the new study, the team “carefully adjusted” for the number of transfusions performed and allowed for the effect of RBC transfusions on mortality to differ between men and women.
“The consequences of the findings from [the earlier studies], if proved true, would have been immense and necessitated radical changes to how blood transfusions are managed around the world,” said Martin Holzmann, MD, PhD, of Karolinska Institutet in Stockholm, Sweden.
“Our results clearly show that there is no real connection between sex-discordant blood transfusions and the risk of death.”
Therefore, Dr Holzmann and his colleagues believe there is no need to consider donor sex when allocating RBC units for transfusion.
To come to this conclusion, the researchers analyzed data on 45,090 patients who underwent cardiac surgery and received at least 1 RBC transfusion.
All patients were adults who had undergone isolated coronary artery bypass grafting, isolated valve repair/replacement surgery, or a combination of these procedures between 1997 and 2012.
The researchers estimated the relative hazard of death in relation to exposure to sex-discordant transfusions, adjusting their analyses for potential confounding factors, such as patient sex, age, blood group, and number of transfusions.
Results
The researchers found that women were more likely to receive sex-discordant transfusions than same-sex transfusions—45.3% and 19.8%, respectively. And patients who received sex-discordant transfusions tended to receive more transfusions—a mean of 4.2 vs 2.0 for same-sex transfusions.
However, there were no other significant differences between the sex-discordant and same-sex groups.
The researchers noted that, during the 30-day follow-up period, there were more deaths among patients who received sex-discordant transfusions than those who did not—1701 (4.9%) and 205 (1.9%), respectively.
However, when the team adjusted for potential confounding factors, the relative risk of death was similar for patients who received at least 1 unit of sex-discordant blood and those who did not. The hazard ratio was 0.97 at 30 days of follow-up, 0.97 at the 2-year mark, and 0.98 at 10 years of follow-up.
The risk of death did increase as the number of sex-discordant units transfused increased. However, the increase was not statistically significant.
