Causes of mortality after haploidentical hematopoietic stem cell transplantation and the comparison with HLA-identical sibling hematopoietic stem cell transplantation

This study was performed to investigate incidence, causes and factors influencing mortality after haploidentical hematopoietic stem cell transplantation (HSCT) and to compare differences between haploidentical HSCT and HLA-identical sibling HSCT. From January 2000 to June 2011, 1411 patients with acute leukemia or myelodysplastic syndrome were included in this study. Of these patients, 571 received HLA-identical sibling HSCT and 840 received haploidentical HSCT. The cumulative incidence of overall mortality and transplant-related mortality (TRM) after haploidentical HSCT was higher than those after HLA-identical sibling HSCT (38.7% vs 33.3%, P=0.012 and 27.5% vs 19.9%, P=0.002), but the incidence of relapse-related mortality (RRM) did not differ between the two groups (15.6% vs 16.7%, P=0.943). A multivariate analysis suggested that high-risk disease status and haploidentical HSCT correlated with a higher incidence of overall mortality (P<0.0001, hazard ratio=1.911 and P=0.019, hazard ratio=1.249); in addition, in haploidentical HSCT, only high-risk disease status correlated with a higher incidence of overall mortality (P<0.0001, hazard ratio=1.845). Our study suggested that haploidentical HSCT provided a higher incidence of overall mortality and TRM but the same incidence of RRM compared with HLA-identical sibling HSCT. Therefore, HLA-identical sibling HSCT remains the first choice, but haploidentical HSCT is available for patients without an HLA-identical sibling donor.