Attrition at the final donor stage among unrelated haematopoietic stem cell donors: the British Bone Marrow Registry experience.

OBJECTIVES: To investigate attrition at the finally selected donor stage among British Bone Marrow Registry (BBMR) donors, all recruited from blood donors. BACKGROUND: The success of searches for unrelated stem cell donors relies on the existence of large international donor registries and the availability of registered donors when matched with a patient. Withdrawal of donors may adversely affect patient outcomes. MATERIALS/METHODS: Data on 2942 planned donations were analysed to assess donor-related deferral rates and associated factors. RESULTS: Overall, 20·2% of requests were cancelled. Transplant centres activated more than half of the cancellations (52·6%). Donor reasons accounted for 46·7% of cancellations (9·4% of requests), of which 61·7% happened for medical and 38·3% for personal reasons. Medical ineligibility of the donor was associated with increasing age (odds ratio [OR] = 1·36, P = 0·011) and peripheral blood stem cell source (OR = 2·22, P = 0·006), and there was some evidence of association with low blood donation reliability (OR = 1·52, P = 0·054). The blood donor reliability score relates to blood donation, and the score worsens if donors consistently fail to attend a donation session when invited. Withdrawal on personal grounds showed associations with donor age (OR = 1·72, P = 0·017, 30-40 years vs other ages), peripheral blood stem cell source (OR = 2·43, P = 0·010) and low blood donor reliability (OR = 1·94, P = 0·007). CONCLUSIONS: To our knowledge, this is the first report on all-cause cancellation at the finally-selected donor stage for international stem cell donor provision, showing 9·4% donor-related cancellation rate. Scores associated with blood donation reliability may be useful to predict stem cell donor withdrawal.

The potential role of HLA-DRB1*11 in the development and outcome of haematopoietic stem cell transplantation-associated thrombotic microangiopathy.

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a serious complication of allogeneic haematopoietic stem cell transplantation (allo-HSCT) with high mortality rate. We retrospectively studied the frequency, clinical and genetic associations and prognostic effect of TA-TMA, in a total of 425 consecutive adult patients, who underwent allo-HSCT for a malignant haematological condition between 2007 and 2013 at our single centre. TA-TMA developed in 19% of the patients. Unrelated donor type (P<0.001), acute GvHD grades II-IV (P<0.001), myeloablative conditioning regimens (P=0.003), tacrolimus-based GvHD prophylaxis (P=0.003), CMV infection (P=0.003) and carriership for HLA-DRB1*11 (P=0.034) were associated with the development of TA-TMA. Survival was adversely affected by the presence of TA-TMA (P<0.001). Among patients with TA-TMA, the outcome of HLA-DRB1*11 carriers was significantly better compared with non-carriers (P=0.003). As a new finding, our observations suggest that the presence of HLA-DRB1*11 antigen contributes to the development of TA-TMA and affects the outcome.