Pre-transplant Comorbidities – Influence on Decision Making and Outcomes

The advent of allogeneic hematopoietic cell transplantation (allo-HCT) brought potential cures to a large number of malignant and non-malignant hematological disorders. Unfortunately, the curative benefits associated with allo-HCT are eclipsed by an increased risk of adverse effects on organ systems. Comorbidities present at the time of transplantation also adversely influence post-transplant outcomes. Combined, these risks complicate patient selection for allo-HCT. To account for this, the HCT comorbidity index (HCT-CI) was developed to predict post-transplant complications, organ toxicities, and acute and chronic graft-versus-host-disease (GVHD), as well as transplant outcomes like morbidity, mortality, and quality of life. The HCT-CI has been verified to be a clinically meaningful tool for the stratification of risk prior to transplant. The predictive power of the HCT-CI can be augmented by the addition of patient- and/or disease-specific risk factors and further expanded by analyzing its utility in conjunction with other available indices. Here we describe the impact of comorbidities on transplant outcomes, the development of comorbidity-specific prediction models, other composite models, their application to guide decision-making, the use of the HCT-CI for autologous transplant, and future directions to refine strategies of predicting post-transplant outcomes.