New research suggests that the sex of a blood donor does not have a significant overall effect on the survival of red blood cell transfusion recipients. A team of investigators led by the Ottawa Hospital in Canada published the findings Thursday in the New England Journal of Medicine.
In this double-blind, randomized trial, investigators randomized 8,719 patients undergoing RBC transfusion to receive RBC units from either male donors or female donors in a 60:40 ratio. A total of 5,190 patients were assigned to the male donor group while 3,529 were assigned to the female donor group. The primary outcome was survival, measured from the date of randomization to the date of death or the end of the trial follow-up period. The mean follow-up was 11.2 months, and the maximum follow-up was 29 months.
During the study period, 1,141 patients in the female donor group and 1,712 patients in the male donor group died. The unadjusted hazard ratio for death was 0.97 (95% confidence interval [CI], 0.90 to 1.05), and the adjusted hazard ratio was 0.98 (95% CI, 0.91 to 1.06). The findings corroborate a 2022 natural experiment in Sweden, which found that donor sex and parity were not associated with increased 2-year mortality risk in RBC transfusion recipients.
The trial also included secondary outcomes, but investigators observed no between-group differences in the secondary outcomes (except for a higher incidence of MRSA infection in the female donor group). While investigators observed subgroup effects in the recipient-sex subgroup and in the subgroup of recipients of RBC units from donors 20 to 29.9 years of age, they believe the inconsistency of the point estimates across groups and the multiplicity of analyses increases the risk that those findings were due to chance.