Unrelated adult stem cell donor medical suitability: recommendations from the World Marrow Donor Association Clinical Working Group Committee.

The World Marrow Donor Association (WMDA) fosters collaboration between international registries to facilitate the exchange of hematopoietic stem cell products for unrelated stem cell donor transplantation. As indications for hematopoietic SCT grow, the movement of products across the world will increase. Although competent authorities may regulate products within their country, there is a need to protect the best interests of donors and recipients by identifying universal donor medical suitability criteria. Within this report the WMDA provides a background to unrelated adult donor and recipient safety, recommends a common framework for assessing the health of unrelated adult donors at each stage of the donation pathway and presents a novel mechanism for sharing international consensus criteria for individual medical and lifestyle conditions. Wherever possible, these criteria are evidence-based. By establishing a donor medical suitability working group, the WMDA has developed a process through which donor centers and registries may request a consensus opinion on conditions not already listed, as well as challenge existing criteria. Guidance from the WMDA is intended to complement, not supersede, guidance from national competent authorities and international regulatory bodies.

Ethnicity, length of time on the register and sex predict donor availability at the confirmatory typing stage.

Despite over 20 million unrelated donors being listed worldwide, donor attrition at the confirmatory typing (CT) stage of donor acquisition is a key source of delay. Anthony Nolan undertook a study of CT requests from 2010 to 2011 to identify factors associated with attrition. Of 7541 CT requests, 38.2% were cancelled for donor reasons. Of these, 19.4% were personal, 34.1% medical, 36% no contact, 7.9% emigrated and 2.6% others. African (odds ratio (OR) 2.78, P<0.001), African-Caribbean (OR 3.07, P<0.001), Asian (OR 2.65, P<0.001), Jewish (OR 1.54, P=0.009) and Mediterranean (OR=2.38, P<0.001) donors were more likely not to be available compared to Caucasian donors. Female donors were also more likely not to be available (OR=1.32, P<0.001): primarily due to pregnancy. Older donors were less likely to be available in univariate analysis, but this association was not significant after controlling for other factors. Blood donors and those recruited within the past five years had lower rates of attrition. Accumulation of additional attrition-associated characteristics for a given donor was associated with progressively greater odds of attrition (OR 1.99, 2.52, 3.4 and 5.53, respectively, for 1, 2, 3 and 4 risk factors, P<0.001). Donor registries must develop evidence-driven strategies to recruit and retain the most reliable donors.

Beating the odds: factors implicated in the speed and availability of unrelated haematopoietic cell donor provision.

The demand for unrelated haematopoietic cell (HPC) donors has risen threefold over the last decade, and is likely to continue to rise over the next 10 years. The time taken from diagnosis to transplant is recognised to adversely affect patient outcome, and provision of unrelated donors (UDs) has been identified as a key source of delay. Obstacles to provision of UD include: delays in referral to a transplant centre, awaiting sibling typing, lack of matched donors (particularly for those from ethnic minorities and/or with rare HLA phenotypes), low- or intermediate-resolution donor HLA typing, donor attrition from the registries, donor ineligibility on grounds of health and difficulties encountered transporting HPC across international borders. There are now over 18 million volunteer donors in registries worldwide, and efficiency has improved, at least in part, because of a switch from paper to electronic searches. As a result, the average time from search request to transplant is estimated to be less than half of what it was two decades ago. Furthermore, registries have developed a number of strategies designed to minimise delays and, ultimately, improve patient outcomes. These include: optimisation of donor numbers and ethnic mix through focused and selective recruitment; high-resolution typing at donor recruitment; cord blood banking with aggressive recruitment in ethnic minorities; early identification of those unlikely to find a match so alternative transplant options may be pursued in a timely manner, through use of HLA-based predictive algorithms; reduction of donor attrition; centralised, registry-based, donor identification services; and provision of a back-up donor.