Effects of Recipients’ Body Weight on Engraftment after Unrelated Bone Marrow Transplantation: Analysis of Clinical Data of 4065 Patients from the Database of the Japan Marrow Donor Program.

In allogeneic bone marrow transplantation from unrelated donor of Japan Marrow Donor Program (JMDP), the standard nucleated cell dose for transplantation is regulated as 3.0x10E8 bone marrow nucleated cells/recipient’s body weight. But if a recipient is heavyweight, it it often diffecult to get enough bone marrow from the donor for transplantation. Infused cell number and recipients’ body weight may infuence the engraftment and outcome of transplantation. We retrospectively analysed the clinical data of 4065 adult transplant recipients (median age 35, range 16–70) from extracted the database of JMDP. Based on the previous studies, the possible factors which could influence on engraftment were collected. The correlations of these factors with engraftment and neutrophil recovery after transplantation were analysed by using multiple logistic regression. Variables correlated with an increased possibility of engraftment were: incrased recipient’s body weight (p<0.001), increased transplanted cells/recipient’s body weight (p=0.0016), younger recipient’s age (p=0.0019) and using TBI for conditioning (p=0.0358). Variables correlated with early attaining of neutrophil>500 were: use of G-CSF after transplantation (p<0.0001), increased transplanted cells/recipient’s body weight (p<0.0001), and no use of MTX for GVHD prophylaxis (p<0.0001). But in the subset analysis of G-CSF use group, first 25 percentile group reached neutrophil>500 significantly earlier than other group (p<0.0001). These results suggested that recipients’ heavy body weight positively influenced on engraftment, but obesity of recipients might delay neutrophil recovery. This study may contribute to consider the adequate cell dose for unrelated bone marrow transplantation and assess the value of recipients’ body weight as a risk factor of hematopoietic cell transplantation.