Recent decrease in non-relapse mortality due to GVHD and infection after allogeneic hematopoietic cell transplantation in non-remission acute leukemia

Although recent improvements have been indicated in the outcome after allogeneic hematopoietic cell transplantation (allo-HCT), little information is available on how changes in transplant modalities have affected the outcomes after allo-HCT in non-remission, based on patient age, donor source and disease type. We compared the incidence and causes of non-relapse mortality (NRM) after allo-HCT in non-remission among three consecutive four-year periods using a nationwide transplant outcome registry database. A total of 3308 patients with acute leukemia in non-remission were analyzed. The risk of NRM decreased over the three periods, and the hazard ratios (HRs) in 2001-2004 and 2005-2008 compared with 1997-2000 were 0.86 (95% CI, 0.70-1.06; P=0.16) and 0.65 (95% CI, 0.53-0.80; P<0.01), respectively. A significant decrease in the HR for overall mortality was also observed in 2005-2008 (HR 0.85; 95% CI, 0.75-0.97; P=0.02). We found that a decrease in the incidences of death due to GVHD and infection contributed to the reduction in NRM, to which high-resolution donor-recipient HLA matching and other improvements may have contributed. As none of the subgroups showed improved survival without a reduction in NRM, the effective prevention of transplant-related complications appears to be necessary for improving outcomes after allo-HCT in non-remission.