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Evaluation of the confidential unit exclusion form: the Canadian Blood Services experience
S F O'Brien1, W Fan, G Xi
1Canadian Blood Services, Ottawa, ON, Canada. sheila.o'brien@blood.ca
Insights
Confidential unit exclusion (CUE) did not improve blood safety by predicting transmissible diseases or high-risk behavior. Its use resulted in the unnecessary exclusion of safe donations, offering no clear safety benefit.
Area of Science:
- Blood Transfusion Safety
- Epidemiology
- Public Health
Background:
- Confidential unit exclusion (CUE) was developed to allow blood donors to exclude donations without disclosing risk factors.
- Many blood establishments have discontinued CUE due to changes in donor behavior, disease epidemiology, and improved testing.
- This study evaluated the effectiveness of CUE in Canada for predicting transmissible diseases and high-risk behavior.
Purpose of the Study:
- To assess the safety benefit of confidential unit exclusion (CUE) in blood donations.
- To determine the utility of CUE in predicting transmissible diseases (TD) and high-risk behaviors among blood donors in Canada.
Main Methods:
- Analysis of TD-positive donations and incident cases between 2004 and 2008, categorized by CUE status (CUE-safe vs. CUE-unsafe).
- An anonymous survey of 40,000 blood donors to gather data on CUE usage, understanding, and self-reported risk factors.
Main Results:
- Out of 4,775,044 donations, 7,104 (0.15%) were designated CUE-unsafe.
- The vast majority of TD-positive donations (99.32%) were CUE-safe; only 0.68% were CUE-unsafe.
- All 95 incident cases, including three NAT-yield cases (1 HIV, 2 HCV), were from CUE-safe donations.
- Donor survey indicated confusion regarding CUE, with only half believing donations would still be tested and a fifth aware of staff visibility.
- No CUE users admitted risk behavior, but 1% of CUE-safe donors reported high-risk behaviors.
Conclusions:
- The study found no evidence that confidential unit exclusion (CUE) provides a safety benefit for blood transfusions.
- CUE usage leads to a consistent loss of donations that are otherwise considered safe.
- The findings suggest that CUE is not an effective tool for identifying high-risk donations or preventing transmissible diseases in the blood supply.
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 (0.15%) donations designated CUE-unsafe of 4,775,044 donations. Most TD-positive donations were designated CUE-safe (1023/1030, 99.32%) with only seven (0.68%) 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 [10.5% (first-time), 3.2% (repeat)], only half thought that the blood would still be tested [48.9% (first-time), 45.9% (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.
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