Increased risk of 100-day and 1-year infection-related mortality and complications in haploidentical stem cell transplantation.

Background: While haploidentical transplantation has led to the near-universal availability of donors, several challenges for this form of transplant still exist. This study sought to investigate the rates of infection-related mortality and other complications following haploidentical vs nonhaploidentical transplant. Methods: We conducted a retrospective cohort study in adults with various malignant and benign hematological conditions who underwent allogeneic hematopoietic stem cell transplantation from 2011 to 2018. One hundred-day and 1-year overall survival were defined as survival from the time of transplant until 100 days or 1 year later. Results: A total of 187 patients were included in this study, with 45 (24.1%) receiving transplants from haploidentical donors and 142 (75.9%) from nonhaploidentical donors. There were similar rates of acute graft-versus-host disease (GVHD) (40% vs 38% in haploidentical vs nonhaploidentical recipients, P=0.86) and chronic GVHD (44.4% vs 43.7%, P=1). Rates of 100-day and 1-year infection-related mortality were significantly higher in the haploidentical group compared to the nonhaploidentical group (8.9% vs 1.4% at 100 days, P=0.03, and 15.9% vs 3.8% at 1 year, P=0.01). There were also higher rates of cytomegalovirus infections (59.1% vs 23.8%, P<0.01), BK virus-associated hemorrhagic cystitis (40.9% vs 8.4%, P<0.01), and BK viremia (15.9% vs 0.8%, P<0.01) in haploidentical recipients. Conclusions: Despite the use of identical antimicrobial prophylactic and treatment agents, haploidentical recipients were found to have significantly increased rates of 100-day and 1-year infection-related mortality as well as several other infectious complications.