Unintentional bias in donor screening

Project Summary


The Canadian blood donation system relies on the participation of volunteer donors and at the same time seeks to screen out high risk donors. Concern exists about whether attempts to screen out high risk donors may inadvertently create negative bias against certain groups—such as men who have sex with men (MSM)—who have historically been screened out. Concern also exists as to whether screening out sexually active MSM is actually effective in screening out individuals who engage in high risk of HIV transmission sexual behaviors. This study focused on the blood donor screening questionnaire then in place and examined whether it may have generated unintentional negative bias against MSM, as MSM screening questions were sandwiched between nine other questions about stigmatized behaviours (illegal drug use, imprisonment, prostitution, and sexually transmitted infections). The study also investigated whether an alternative questionnaire based on a behaviour-based screening approach would be more effective than the current questionnaire to screen for high-risk donors.

What was done?

This was a national, randomized online study of 1,000 Canadian Blood Services’ donors. Participants completed either the standard donor eligibility questionnaire with the question about MSM sexual activity positioned within a cluster of items concerning stigmatized behaviors or a modified version of the donor screening questionnaire that re-positioned the MSM sexual activity question among more neutral items. After completing the standard or modified donor questionnaire, bias against MSM was measured using a gay-straight Implicit Association Test (a reaction time measure of the association of ‘gay” and “straight” with positive or negative attributes) and the Modern Homonegativity Scale (a measure of negative attitudes towards homosexuals). Participants were also asked to estimate the prevalence of certain stigmatized behaviours not characteristic of MSM, amongst MSM. Finally, participants were asked about their own sexual behaviours that increase HIV transmission risk (e.g. condom-less sex with multiple partners in the past year).

What was found?

Blood donors who completed the standard donor questionnaire expressed negative bias toward MSM compared to those who completed the modified donor questionnaire when completing the Implicit Association Test. Direct measures of attitudes towards MSM and estimates of stigmatized behaviours among MSM did not differ between donors who completed the standard vs. modified questionnaire. Among blood donors who did not report MSM sexual behaviour, 8.6% reported unprotected penile—vaginal sex with more than one partner during the past year and 1.0% reported unprotected penile—anal sex with more than one partner during the past year.

Opportunities for change

Results show that the standard donor questionnaire may unintentionally generate bias against MSM. These findings provide evidence to support repositioning the MSM screening question so that it is not embedded with stigmatized behaviour items. Since the content of the questionnaire would not be changed, any recommendations to change the order of the questions should be easily implemented. Broadly, these results suggest that something as simple as the order of questions on a questionnaire can have negative impacts on donor perceptions; policy makers must be mindful of this when designing future iterations of the donor eligibility questionnaire. Additionally, assessment of specific HIV transmission risk behaviours detected a nontrivial level of HIV risk in eligible donors that was not detected by the MSM screening question. These results support moving to specific behavioural questions to screen for blood donor sexual behaviours that increase the risk of HIV transmission. On June 3, 2019, the MSM deferral period was been reduced to 3 months. The MSM screening question is currently being repositioned on the donor screening questionnaire. Subsequently, a behavior based screening procedure was implemented and all donors are screened for potential transfusion transmitted infection.

Future considerations

Although the results of this study suggest that a behaviour-based questionnaire might screen out some currently eligible blood donors who are at elevated risk of HIV transmission, we did not assess how blood donors would react to questions about specific sexual practices. Our subsequent research within the MSM Plasma Program funding envelope explored this specific issue comprehensively. A behaviour based questionnaire might allow some low-risk MSM to donate blood but might deter non-MSM populations from donating. In fact, results of our subsequent research indicated that a behavior based screening of all blood donors was highly acceptable to current donors, as indicated in now published research by Fisher and colleagues (Fisher et al., 2023)

Research publications

Hofkirchner, A., Kohut, T., O'Brien, S. F., & Fisher, W. A. (2022). Assessing unintentional creation of bias against men who have sex with men as a function of exposure to blood donor screening questionnaire: A national randomized controlled trial. Transfusion, 62(7), 1399–1407. https://doi.org/10.1111/trf.16930.

Fisher, W. A., Kohut, T., Woo, H., & Haw, J. (2023). Alternatives to blood donor deferral of gay, bisexual, and other men who have sex with men: Acceptability of screening the sexual risk behavior of all blood donors. Transfusion, 63(3), 531–540. https://doi.org/10.1111/trf.17241


Findings from this research directly informed a re-organization of questions in CBS' Donor Health Questionnaire (implemented December 2020) to reduce unintentional biases against gay, bisexual and other MSM. This research also informed our overall approach to implementation of sexual behaviour based screening and how we approach issues of inclusivity in our donor screening.