Impact of geographic distance from transplant center on the risk of severe graft-versus-host disease after allogeneic hematopoietic cell transplantation.

Abstract

e23055 Background: Geographic distance to care has been associated with outcomes in solid tumors, reflecting differences in access, follow-up, and supportive care. However, its relationship with biologic transplant toxicities such as graft-versus-host disease (GVHD) has not been well characterized. Understanding whether access-related factors are associated with immune-mediated complications is important for systems-level optimization of post-transplant care and survivorship. Methods: We conducted a retrospective cohort study of adult patients undergoing allogeneic hematopoietic cell transplantation using the CIBMTR hs1802 publicly available dataset. Distance from patient residence to the transplant center was categorized as less than 20 miles, 20 to 50 miles, 50 to 150 miles, and greater than 150 miles, with less than 20 miles as the reference group. Primary outcomes were acute GVHD and chronic GVHD within one year after transplantation. Secondary outcomes included overall survival. Multivariable Cox proportional hazards models were used to evaluate associations between distance and outcomes, adjusting for age, sex, race and ethnicity, HCT comorbidity index, conditioning intensity, donor type, GVHD prophylaxis, transplant era, disease type, and total body irradiation use. Results: A total of 5,473 patients were included, with a median follow-up of 60.2 months. Crude rates of acute GVHD increased with greater distance from the transplant center, occurring in 40.2 percent of patients living less than 20 miles away and 45.1 percent of those living more than 150 miles away. In adjusted analyses, residence more than 150 miles from the transplant center was associated with a higher risk of acute GVHD compared with less than 20 miles, with an adjusted hazard ratio of 1.15 and a 95 percent confidence interval of 1.00 to 1.31. No significant differences were observed for intermediate distance categories. For chronic GVHD within one year, patients living more than 150 miles away had a lower recorded risk compared with those living less than 20 miles away, with an adjusted hazard ratio of 0.79 and a 95 percent confidence interval of 0.71 to 0.88. Distance to transplant center was not significantly associated with overall survival. Conclusions: Greater geographic distance from transplant centers is associated with a higher risk of severe GVHD after allo-HCT. These findings suggest that access to specialized post-transplant care and close monitoring may influence immune-mediated outcomes. Strategies to improve follow-up care, including enhanced care coordination and telemedicine, may help mitigate GVHD-related disparities and inform health policy efforts aimed at improving access to specialized transplant services, reimbursement for remote monitoring, and regional models of post-transplant care delivery.