Impact of Pre-existing Comorbidities on Outcomes After Allogeneic Hematopoietic Cell Transplantation

Overview

This retrospective EBMT study analyzed the influence of pre-existing comorbidities on non-relapse mortality (NRM) and other outcomes following allogeneic hematopoietic cell transplantation (allo-HCT) in adults with hematologic malignancies. The study found that while comorbidities remain important predictors of NRM, their impact may be attenuated compared to earlier cohorts due to advances in transplant practices and supportive care.

Background

Allogeneic hematopoietic cell transplantation is a potentially curative therapy for hematologic malignancies but is associated with significant treatment-related mortality, primarily from graft-versus-host disease, infections, and conditioning toxicity. The Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) was developed to quantify the impact of pre-existing comorbidities on transplant outcomes, particularly non-relapse mortality. Given improvements in donor selection and supportive care, the predictive value of the HCT-CI requires re-evaluation in contemporary transplant populations. The EBMT registry collects comprehensive data on comorbidities and outcomes, enabling this large-scale retrospective analysis.

Data Highlights

The study included adult patients undergoing first allo-HCT between 2010 and 2018 with complete comorbidity data. Pre-existing comorbidities assessed included solid tumors, inflammatory bowel disease, rheumatologic disease, infections requiring ongoing treatment, diabetes, renal and hepatic disease, pulmonary disease, cardiac and cerebrovascular conditions, obesity, peptic ulcer, and psychiatric disturbances. Outcomes analyzed were non-relapse mortality, overall survival, progression-free survival, relapse incidence, and graft-versus-host disease incidence and severity.

Key Findings

• Pre-existing comorbidities were significantly associated with increased non-relapse mortality after allo-HCT, confirming their continued prognostic relevance.
• The magnitude of the association between comorbidities and NRM was lower than originally reported in the initial HCT-CI development cohorts, suggesting improved transplant outcomes over time.
• Specific comorbidities such as moderate/severe pulmonary disease, renal impairment, and active infections were among the strongest predictors of higher NRM.
• Comorbidity assessment using the EBMT registry data allowed validation and refinement of risk stratification models in a large, contemporary transplant population.
• Improved donor selection, conditioning regimens, and supportive care likely contributed to the reduced impact of comorbidities on mortality.

Clinical Implications

Clinicians should continue to assess pre-existing comorbidities when evaluating allo-HCT candidates, as these remain important predictors of non-relapse mortality. However, advances in transplant techniques and supportive care may mitigate some risks associated with comorbid conditions. Updated risk models incorporating contemporary data can better inform patient counseling and individualized transplant planning.

Conclusion

This EBMT registry analysis confirms that pre-existing comorbidities remain relevant predictors of outcomes following allo-HCT but with a diminished impact compared to earlier cohorts. Ongoing evaluation of comorbidity indices is essential to optimize risk assessment in the evolving transplant landscape.

References

1. EBMT Registry Data and Guidelines
2. Sorror et al. 2005 -- Development of the Hematopoietic Cell Transplantation Comorbidity Index
3. Clinical Practice Guidelines for GVHD Grading and Management