Prognostic effect of body mass index in patients with acute leukemia undergoing allogeneic hematopoietic stem cell transplantation: A retrospective cohort study.

Obesity is a well-known risk factor for many diseases, but the impact of baseline body mass index (BMI) on the outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains controversial. To elucidate the influence of pretransplant BMI on post-allo-HSCT outcomes including graft-versus-host disease (GVHD), overall survival (OS), relapse-free survival (RFS), and nonrelapse mortality (NRM), we conducted a retrospective study using registry data which comprised 1092 adult patients who underwent allo-HSCT between 2015 and 2023. Among the 1092 eligible patients (53.2% male), 56.5% were normal-weight; 24.8% were overweight and 9.1% were obese. Multivariable analyses revealed that compared with normal-weight patients, obese individuals had a higher risk of grade II-IV and III-IV acute GVHD (aGVHD), especially in the gastrointestinal system, with aHRs of 2.08 (95% CI, 1.47-2.94), 2.60 (95% CI, 1.52-4.44), and 3.71 (95% CI, 2.00-6.88), respectively. The probability of OS and RFS was significantly lower in overweight (P = 0.034, P = 0.015, respectively) and obese patients (P = 0.033, P = 0.024, respectively) as compared with normal-weight patients, with aHRs increasing by ~38% (aHR, 1.38; 95% CI, 1.03-1.86), ~40% (aHR, 1.40; 95% CI, 1.07-1.83), ~58% (aHR, 1.58; 95% CI, 1.04-2.40), and ~56% (aHR, 1.56; 95% CI, 1.06-2.29), respectively. Furthermore, the NRM of obese patients was statistically higher than normal-weight patients (P = 0.02, sHR, 2.19; 95% CI, 1.12-4.27). A subgroup analysis revealed that the adverse effects of obesity on OS, RFS, and NRM were primarily observed in the subgroup of patients aged < 40 years and patients with acute lymphoblastic leukemia. The increased risk of grade II-IV aGVHD due to obesity was observed across all subgroups. In conclusion, Obesity prior to allo-HSCT increases the risk of aGVHD and NRM, leading to poorer OS. These findings underscore the importance of closely monitoring high-risk patients and offering opportunities for early intervention.