Infections in blood donors can be transmitted to blood product recipients. Strategies to reduce the risks to blood product recipients have involved public education programs, administration of questionnaires pertaining to HIV risk factors, the use of a confidential self-exclusion (CSE) option which allows the donor to indicate in a confidential manner that their blood should not be used for transfusion, and direct questioning about risk behaviours. These strategies have been found to eliminate some high risk 12 and some infected units 3. While there have been notable decreases in HIV-positive donations 45, some donors, who are aware of their high-risk behaviours continue to donate without self-deferral 36789.

Serologic testing is now performed on all acceptable donors in Canada. In the past, window-period infections have been a concern, however the use of highly sensitive nucleic acid amplification technology (NAT) has now reduced this risk of a transfusion-transmitted infection due to a window-period donation to an estimated one per million donations or fewer in the U.S.1011. In Canada, NAT is used for HIV and HCV screening in blood donors (http://www.bloodservices.ca, accessed March 1, 2002).

Despite the small risk of infection from donated blood, there is strong public pressure to ensure that all measures to reduce the risk of transfusion-transmitted infection are used. A potential role for improved risk factor detection through pre-donation screening would be to reduce the risks from as yet unknown blood borne diseases if these diseases were associated with other known risk groups. Explicit direct questions instead of indirect references to high-risk behaviours for HIV/AIDS have been shown to increase self-deferral rates in donors at least two-fold 1213. It has been estimated that the standard donor health assessment questionnaire may miss as many as 10% of donors who engage in high-risk behaviours 6. Studies using various computerized questionnaire methods have found increased reporting of perceived socially undesirable behaviors compared to face-to-face interviews in higher risk groups 14151617, however few have assessed the usefulness or acceptability of computer-assisted screening in the blood donation screening process 1819.

This randomized crossover trial among blood donors compared a self-administered computerized questionnaire (HealthQuiz, or HQ) to the existing Donor Health Assessment Questionnaire (DHAQ) on consistency of responses. We also assessed the acceptability and ease of administration of the HQ in the donors.

Using the computerized HQ, the number of donors that were eventually deferred was nearly double the number that was deferred based on the written DHAQ, and eleven donors indicated on the computerized HQ that there was some reason they should not donate blood on that day, but did not use the CSE option on the DHAQ. Risks related to blood-borne infections accounted for a small number of the items identified by the HQ that were not identified by the DHAQ, however the detection of even a small number of such individuals could potentially prevent a high risk donation. Although there were no seropositive donors in this study, the HQ identified additional donors who may have been at increased risk of acquiring a blood borne infection through various risk behaviours. The identification of high risk donors also has important implications for avoiding as yet unknown blood-borne infections.

Our finding, that the computerized HQ identified 2.4% of donors with risk factors for HIV/AIDS and sexually transmitted infections that were not identified on the written DHAQ is not unique. In a randomized crossover trial in the U.S., an additional 4.4% of donors with HIV risks or AIDS symptoms were identified when using a computer-based interview which asked about activities that place them at high risk for HIV, compared to the American Red Cross standard written questionnaire and interview 20. Another study in the U.S. suggests that people may be more likely to respond truthfully about risk behaviours when questioning is anonymous 21. In that study, a questionnaire mailed one to two months following a donation identified a risk factor that should have resulted in deferral of their donation among 2% of respondents. Of the respondents who reported risks only on the mailed survey, 8% of their donations had been rejected for transfusion due to a positive laboratory test.

Previous survey research on sexual behavior, smoking, alcohol, and drug use, has found that use of a computer-assisted questionnaire increased reporting of "stigmatized" behaviors compared to face-to-face interviews 141516172223. However, some of these studies 161723 were limited by the lack of random allocation or randomized cross-over of the participants to the different screening methods, therefore it cannot be determined whether the differences in reporting were due to the different screening methods rather than differences in participants characteristics. In addition, all but one 22 of these studies were conducted in injection drug users at a needle exchange program, in gay men, and in women attending a sexually transmitted diseases clinic, therefore the results may not be generalizable to blood donor populations.

The finding in the present study that the computerized screening approach was feasible and acceptable to donors is similar to previous studies 1819. Comfort with the screening process and privacy of responses are important issues in eliciting accurate and honest responses. In a previous study, donors with unreported deferrable risk factors and with reactive infectious disease screening reported being more likely to disclose personal information to a computer 18.

A limitation of the present study and of other literature comparing two methods of self-reported information 1516172223, was our inability to conclude that the HQ identified high-risk donors, in the absence of a gold standard. Since none of the donors in the present study were reactive for transmissible infections, we used deferral as a surrogate marker for high risk donors. Other studies in North America have also reported low rates of antibodies in blood donors. The sero-prevalence of HIV was 0.02% among 123,608 Canadian donors during 1985 6 and was 0.03% in the U.S. among blood donors in 1995 21. Despite the current low seroprevalence of infections in blood donors in North America, a recent study has found that new cases of HIV, HCV, and HBV were as common among frequent donors as among infrequent donors 24, suggesting that caution must still be used in blood donor screening strategies.

Previous research has suggested that the limitations of screening questionnaires in identifying ineligible donors may in part be due to the donors' failure to carefully read the instructions or understand the information 8. In one study, some HIV-positive donors failed to exclude their donated units because of difficulty understanding the written explanation of the self-exclusion process 25. While it may be that donors were more willing to disclose facts that made them ineligible for blood donation on a computerized questionnaire, other factors could have influenced the responses. Most of the donors were repeat donors and were familiar with the written DHAQ questions and format. Therefore, some donors may not have read the questions carefully, leading to inaccurate answers. The items for which the largest number of donors answered negative on the DHAQ but positive on the HQ were items which had multiple individual questions on the HQ but were listed in one question on the DHAQ. The high frequency of reporting on the HQ for items such as having heart or blood pressure problems or heart surgery (17.4%), and a kidney, lung or blood condition (12.0%) is surprising and suggests that some donors may not have understood or carefully read these questions. Affirmative answers to these questions on the DHAQ would have led to further review of the responses with the clinic staff and would have likely resulted in changes to the responses, otherwise the deferral rate would have been much higher. Without further staff investigation, healthy risk-free donors could mistakenly be deferred if questions on a self-administered questionnaire are not understood. These results highlight the need for careful evaluation of a computerized screening process to ensure that accurate information is obtained without burdening clinic staff.

A computerized questionnaire may improve the efficiency of the donor screening process. The computer was easy to use and the data that were entered into the computer were immediately available as a printed report and in electronic medium for storage. Transcription errors were eliminated and the database was complete for each potential donor. A limitation of this study was the inability to compare the efficiency of the deferral process using the HQ to the usual process using the written instrument, since no information regarding staff resources was obtained.

In response to the increasingly complex and time-consuming donor screening process, computer-assisted screening is currently in place in some areas, and the U.S. Food and Drug Administration (FDA) has recently provided draft guidelines for the use of self-administered questionnaires including those that are computer-assisted 2627. The FDA recommends assessment of the effectiveness of self-administered questionnaires in identifying unsuitable donors. The randomized cross-over trial is a useful methodology for this type of assessment, both to identify unclear or problematic questions and to have a valid comparison of responses to the two methods within each individual. Studies presenting different testing methods to different individuals, especially in a non-randomized fashion, cannot provide such comparisons.

While the risk to blood product recipients of contracting infections from blood products has been dramatically reduced with the use of new diagnostic technologies, this study suggests that it may be possible to further improve the blood donor screening process. In addition to excluding high-risk donors, donor health assessment is carried out to include healthy risk-free donors and to protect individuals with medical conditions from possible adverse effects of donating. While we cannot conclude that the increased number of deferrals and risk factors identified in this study resulted in an improvement in the donor screening process, a computerized instrument may have the potential to improve this process if more truthful answers are elicited.

None declared

JWS contributed to the study conception and design and critically revised the manuscript, RH and GS contributed to the study conception and design and in the analysis and interpretation of the data, AA contributed to the study conception and design and acquisition of the data, RBH contributed to the study conception and design and critically revised the manuscript, RB contributed to acquisition and in the analysis and interpretation of the data, KAM contributed to the analysis and interpretation of the data, LL contributed to the acquisition of the data, DD contributed to analysis and interpretation of the data, and MH contributed to analysis and interpretation of the data and critically revised the manuscript.

All authors have read and approved the final manuscript.