Pre-donation screening for blood safety: comparison between 3- and 6-month deferral of men who have sex with men and the incorporation of individual risk assessment

INTRODUCTION: Advances in blood donor screening have supported the shortening of deferral intervals and incorporation of individual risk assessment. This study investigated the potential impacts of comparing 3‑ and 6‑month deferral periods for men who have sex with men and introducing a behaviour‑based individual risk assessment policy in Hong Kong, particularly on donor eligibility and blood safety. METHODS: A cross-sectional study was conducted in March 2024, recruiting individuals who had successfully donated blood in October 2023 in Hong Kong. Participants completed a survey on transfusion-transmissible infection risk-related deferrable behaviours, as described in the pre-donation screening questionnaire, and the United States Food and Drug Administration-proposed individual risk assessment items within 6 months before donation. Bivariable and multivariable (backward) logistic regression analyses were performed to identify factors associated with non-compliance. Presumptive non-compliance rates were calculated based on the timing of the most recent reported risk behaviour. RESULTS: Of 2268 responses received, 1720 (median age=46 years; 50.8% male) were analysed. The non-compliance rate under the prevailing 6-month deferral policy was 4.01% (95% confidence interval [95% CI]=3.16%-5.02%). Non-compliant donors were more likely to be male (adjusted odds ratio [aOR]=2.049, 95% CI=1.216-3.451) and to perceive themselves as healthy (aOR=1.248, 95% CI=1.024-1.521), but less likely to believe in personal responsibility for blood safety (aOR=0.846, 95% CI=0.766-0.935). Presumptive non-compliance rates were 2.79% for 3-month deferral under the prevailing policy and 2.27% for 3-month deferral incorporating individual risk assessment. Of the five individuals who would have been deferred for male-to-male sexual activities under the prevailing policy with a 3-month deferral period, two would have become eligible under individual risk assessment. CONCLUSIONS: Shortening deferral intervals had modest effects on donor compliance. Incorporating individual risk assessment could improve identification of potential donors with higher-risk sexual behaviours while moderately expanding the donor pool.