Obesity Is Associated with An Increased Risk of Infectious Diseases after Unrelated Bone Marrow Transplantation

(Background) Both obesity and malnutrition have been considered to be risk factors for complications after bone marrow transplantation (BMT). To elucidate the impact of pre-transplant body mass index (BMI) on the clinical outcome, we performed a retrospective cohort study with registration data from the Japan Marrow Donor Program (JMDP).

(Results) From January 1998 to December 2005, 3935 patients received unrelated BMT through JMDP, and 3827 patients for whom pre-transplant height and weight data were available were included. Patients were stratified according to pre-transplant BMI values (low BMI: BMI<18, n=295; normal BMI: 18≤BMI<25, n=2906; overweight: 25≤BMI<30, n=565; obese: 30≤BMI, n=61). In a univariate analysis, pre-transplant BMI was associated with a significantly higher risk of grade II-IV acute graft-versus-host disease (GVHD, P=0.03). Other factors which was associated with higher incidence of grade II-IV acute GVHD was HLA allele disparity, GVHD prophylaxis with CSP compared with TAC and donor age (≥40). Multivariate analysis showed that pre-transplant BMI tended to be associated with an increased risk of grade II-IV acute GVHD (P=0.07). Obesity was associated with an increased risk of infectious diseases compared with normal BMI [odds ratio (OR) 1.9; 95% confidence interval (CI) 1.1–3.2; P=0.02]. Progression-free survival was 54%, 52%, 56% and 47% in low BMI, normal BMI, overweight and obese, respectively in 1 year after BMT, and there was a trend that 1-year non-relapse mortality was higher in obese group (low BMI 29%, standard BMI 31%, overweight 32%, obesity 39%).

(Conclusions) This study shows the correlation between pre-transplant BMI and posttransplant complications. Although BMI strongly depends on multiple factors, the effect of obesity on clinical outcome, as suggested here, should be evaluated in a prospective study.