Significantly Higher Rates of Donor Attrition in Minority Ethnic, Female and Older Donors: A Review of 7542 Confirmatory Typing Requests at Anthony Nolan

The confirmatory typing (CT) stage of unrelated donor acquisition is a key source of delays to haematopoietic cell provision. Identifying factors that might predict donor deferral at this stage is important in reducing this delay and improving patient outcome.

METHODS

All CT requests made from Anthony Nolan between 2010-11 were reviewed, and reason for deferral and donor characteristics documented. Associations were determined using multivariate logistic regression analysis.

RESULTS

Of 7542 requests, 56.3% were completed, 38.2% cancelled for donor reasons and 5.5% cancelled for transplant centre reasons. Of donor cancellations 19.4% were personal, 34.1% medical, 36% no contact made, 7.9% overseas/emigrated and 2.6% other. When compared to UK/North European donors, African (OR 2.56, p=0.001), Afro-Caribbean (OR 2.13, p<0.001), Asian (OR 2.45, p<0.001) and Mediterranean donors (OR 1.93, p=0.005) were more likely to defer for donor reasons. Female donors were more likely to defer for donor reasons (OR 1.19, p=0.001), even when pregnancy was excluded. This may be partly explained by more medical deferrals (54% vs 46%). Donor age was also associated with deferral, with more deferred aged 31-45 (OR 1.20, p=0.002) and 46-60 (OR 1.43, p<0.001), compared to 18-30. This difference is largely explained by higher rates of medical deferral (20.9% vs 34.6% vs 45.8% of all donor cancellations for donors aged 18-30, 31-45 and 46-60 respectively), despite older donors being more easily contacted, with fewer personal deferrals. Of medical deferrals, 19.4% of donors were deferred for morbid obesity (BMI>35), 14.4% for malignancy, 11.1% autoimmune conditions, 10.6% cardiac, 5.3% back complaints and 7.1% diabetes. Blood donors were less likely to be deferred for donor reasons (OR 0.72, p<0.001).

CONCLUSION

Despite over 20 million unrelated donors listed on registers worldwide, high rates of donor attrition considerably attenuate this resource and have a significant impact on donor provision. Donors from some ethnic minorities have a particularly high rate of attrition. As a registry, we are employing a number of strategies to address the results of this study: increasing the base of younger donors by reducing the joining age to 16-30, donor pre-activation, use of social media to maintain contact with donors and in depth interviews with those donors who choose not to proceed.