Risk of transfusion-transmitted infections among returned high-risk deferred donors: A cohort study

Blood donor selection is crucial for ensuring safe blood supply. A well-designed donor selection system helps in maintaining donor engagement by minimizing unnecessary exclusion while safeguarding transfusion safety. We aimed to assess the risk of transfusion-transmitted infections (TTIs) among high-risk deferred donors to evaluate deferral criteria efficacy.

This study included data from volunteers who were temporarily deferred because of bloodletting, high-risk sexual contact, tattooing, endoscopy and needle sticks, as well as from eligible donors who donated blood over a 12-month period. These donors were followed up for 4 years. The results of infectious confirmatory tests, including hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV), of returned donors who donated blood were extracted from the database. Risk ratio (RR) of TTI was calculated to compare the risk between eligible and deferred donors.

The data from 601,177 returned, deferred and eligible blood donors were analysed. The risk of TTIs was significantly higher in the deferred group compared to eligible donor group (RR: 3.58; 95% confidence interval [CI]: 2.68-4.80; p <0.001). The risk of TTIs was significantly higher in those deferred for bloodletting (RR = 4.85; 95% CI: 3.41-6.91; p < 0.001), tattooing (RR = 3.53; 95% CI: 1.26-3.83; p = 0.029) and high-risk sexual contact (RR = 2.19; 95% CI: 1.26-3.83; p = 0.011).

Individuals with a history of bloodletting, tattooing or high-risk sexual contact were at a higher risk of HBV and HCV infection, highlighting the effectiveness of donor selection procedures. Endoscopy and needle stick injuries were not associated with an increased TTI risk, emphasizing the need for further research to reassess these deferral criteria. Blood centres should monitor the efficacy of donor selection criteria while emphasizing proper donor selection and counselling.