International Assessment of Blood Donor False-positive Infectious Disease Screening Rates and Re-entry Practices: A BEST Collaborative Study.

False-positive infectious disease screening results in blood donors can lead to unnecessary donor deferral, emotional distress, and loss of future donations. We aimed to evaluate false-positive rates and re-entry practices across several international blood collectors. In this multinational retrospective study, 17 blood collectors provided data from January 2021 through December 2023 on infectious disease screening algorithms/methodologies, false-positive rates for HIV, HBV, HCV, and syphilis, and donor re-entry processes and rates. Participants also reported deferral policies and donor communication strategies. Donor data were stratified and analyzed using descriptive statistics by donor type (first time vs repeat), registration as male or female, calendar quarters, and jurisdiction. Across more than 28 million whole blood donations, false-positive rates per 10,000 tests were low for all screened pathogens: HIV (5.27, 95% confidence interval [CI] = 5.19-5.36), HBV (6.10; 95% CI = 6.01-6.19), HCV (5.20; 95% CI = 5.12-5.28), and Treponema pallidum (syphilis) (10.89; 95% CI = 10.77-11.01). Using chi-square test, false-positive rates differed significantly among pathogens (P < .0001), but rates were consistent across jurisdictions, testing platforms, and years. Seasonal variation was detected in the Northern hemisphere using 2-proportion z-tests with Bonferroni correction. First-time donors demonstrated higher false-positive rates for all markers. Blood collectors reported a range of re-entry reinstatement rates during the 3-year period. False-positive rates were low across jurisdictions for all pathogens screened and remained stable over time, especially among repeat donors. Re-entry programs reported different donor outreach efforts and success in re-qualifying donors (for HIV mean 15.7%, range 0%-39%; for syphilis mean 17.9%, range 0%-44.3%).