Bone marrow transplantation outcomes in obese vs. non-obese patients: A multicenter propensity-matched Study

Abstract Background: Bone marrow transplant is a life-saving treatment for many hematologic disorders, but the success can be influenced by a patient's health status. Obesity is a well-known global health issue and a contributor to significant health problems. Research so far has shown mixed results about its impact on patients with bone marrow transplantation. This study aims to evaluate differences in transplant outcomes between patients with and without obesity. Methods: This retrospective cohort study utilized the TriNetX database, a global federated health research network providing access to medical records for approximately 250+ million de-identified patients. The cohorts were queried on 08/03/2025. We evaluated outcomes in bone marrow transplant recipients with and without obesity. Propensity score matching was employed to control for differences in demographic and clinical characteristics, including age, gender, and comorbid conditions, thereby ensuring a balanced comparison between the two groups. Results: Before propensity score matching, notable differences were observed in the demographic and clinical characteristics of the cohorts. Significant disparities were evident across racial and ethnic groups (p < 0.001). Patients classified as obese exhibited a greater burden of comorbid conditions, including hypertension (48% vs. 36.8%, p < 0.001), diabetes mellitus (23.3% vs. 13.1%, p < 0.001), and chronic kidney disease (13.5% vs. 11.3%, p < 0.001). Gender distribution also varied, with the obese group comprising fewer males (48.7% vs. 53.3%, p <0.001) and more females (42% vs. 37.8%, p <0.001). These differences were balanced following 1:1 propensity score matching, underscoring the effectiveness of the matching methodology. The final matched cohorts each included 11,083 patients undergoing bone marrow transplantation with and without obesity, respectively. Post-matching analyses demonstrated that obesity was associated with significantly higher risks of adverse clinical outcomes. Obese individuals had increased odds of transplant rejection (OR 1.219, 95% CI 1.068-1.392, p = 0.003), graft failure (OR 1.268, 95% CI 1.106-1.454, p = 0.001), and infectious complications (OR 1.670, 95% CI 1.035-2.693, p = 0.034). The obese cohort demonstrated significantly higher mortality (OR 1.123, 95% CI 1.057-1.193, p < 0.001), along with elevated risks of heart failure (OR 2.331, 95% CI 2.146-2.532, p < 0.001), acute kidney injury (OR 2.557, 95% CI 2.389-2.738, p < 0.001), acute respiratory distress syndrome (OR 1.708, 95% CI 1.438-2.029, p < 0.001), cerebral infarction (OR 1.608, 95% CI 1.378-1.876, p < 0.001), sinusoidal obstruction syndrome/veno-occlusive disease (OR 1.598, 95% CI 1.109-2.304, p = 0.0112), acute graft-versus-host disease (OR 1.464, 95% CI 1.331-1.611, p < 0.001), and chronic graft-verus-host disease (OR 1.214, 95% CI 1.112-1.326, p < 0.001). Conclusions: Obesity is associated with significantly worse outcomes in bone marrow transplant recipients, including higher risks of mortality, graft rejection, and transplant-related complications. Specifically, obese patients showed increased odds of heart failure, acute kidney injury, acute respiratory distress syndrome, cerebral infarction, sinusoidal obstruction syndrome/veno-occlusive disease, as well as both acute and chronic graft-versus-host disease. These associations persist even after accounting for baseline differences using propensity score matching. The findings emphasize the need for careful monitoring and individualized management approaches in obese patients undergoing bone marrow transplantation. This study also demonstrates the utility of propensity score matching in evaluating the independent impact of obesity on transplant outcomes.