Evaluation of the confidential unit exclusion form: the Canadian Blood Services experience

Background In the mid-1980s, confidential unit exclusion (CUE) was implemented to permit donors unwilling to admit risk factors in screening to exclude their donation from transfusion. With changes in donor behaviour, epidemiology of disease and improvements in testing, many blood establishments have stopped using it. We evaluated its benefit in Canada, and reported its utility in predicting transmissible-disease (TD) and high-risk behaviour. Study Design and Methods TD-positive donations and incident cases between 2004 and 2008 were analyzed in CUE-safe and CUE-unsafe designated donations. An anonymous survey of 40 000 donors asked about CUE use and risk factors. Results There were 7104 (0 center dot 15%) donations designated CUE-unsafe of 4 775 044 donations. Most TD-positive donations were designated CUE-safe (1023/1030, 99 center dot 32%) with only seven (0 center dot 68%) designated CUE-unsafe. Of 95 incident cases, all were designated CUE-safe including three NAT-yield cases (1 HIV and 2 HCV). In the survey, some donors found the CUE difficult to understand [10 center dot 5% (first-time), 3 center dot 2% (repeat)], only half thought that the blood would still be tested [48 center dot 9% (first-time), 45 center dot 9% (repeat)], and about a fifth believed that collection site staff could see their designation. No survey respondents who used the CUE admitted to risk behaviour, but about 1% of donors who designated CUE-safe had high-risk behaviours. Conclusion The data do not provide any indication of a safety benefit from CUE, but CUE use results in a small but constant loss of apparently safe donations.