for the Japan Marrow Donor Program Both obesity and malnutrition are considered risk factors for complications after bone marrow transplantation (BMT). To elucidate the impact of pretransplantation body mass index (BMI) on clinical outcome, we performed a retrospective cohort study with registration data from the Japan Marrow Donor Program (JMDP). Between January 1998 and December 2005, a total of 3935 patients received unrelated BMT through the JMDP; of these, 3827 patients for whom

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... ntation height and weight data were available were included in the study. Patients were stratified according to pretransplantation BMI values (low BMI: BMI \18 kg/m 2 , n 5 295; normal BMI: 18 # BMI \ 25 kg/m 2 , n 5 2906; overweight: 25 # BMI \30 kg/m 2 , n 5 565; obese: 30 kg/m 2 # BMI, n 5 61). In a univariate analysis, pretransplantation BMI was associated with a significantly greater risk of grade II-IV acute graft-versus-host disease (GVHD; P 5 .03). Multivariate analysis showed that pretransplantation BMI tended to be associated with an increased risk of grade II-IV acute GVHD (P 5 .07). Obesity was associated with an increased risk of infection compared with normal BMI (odds ratio 5 1.9; 95% confidence interval 5 1.1 to 3.2; P 5 .02). Our findings demonstrate a correlation between pretransplantation BMI and posttransplantation complications. Although BMI depends strongly on multiple factors, the effect of obesity on clinical outcome should be evaluated in a prospective study.