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Sex-specific association between body mass index and mortality after heart transplantation: A nationwide KOTRY Cohort Study

Year: 2026

Type: article

Abstract: Background: Body mass index has paradoxical associations with outcomes in advanced heart failure, but whether its relationship with survival after heart transplantation differs by sex remains uncertain. Methods: We analyzed 1059 adult heart transplant recipients enrolled in the Korean Organ Transplantation Registry from 2014 through 2023. Body mass index was assessed using Asian-specific BMI categories and 3-knot restricted cubic splines. The primary outcome was all-cause mortality. Multivariable Cox models adjusted for prespecified clinical characteristics and pretransplant support. Sex differences in the body mass index-mortality association were evaluated using restricted cubic spline modeling. Results: The cohort included 304 female patients, and 217 deaths occurred during a median follow-up of 3.6 years. The body mass index-mortality association differed by sex in the pooled spline model (P for interaction=0.041). In male patients, the association was nonlinear and U-shaped (P for overall association=0.031; P for nonlinearity=0.017). Underweight was associated with higher mortality than normal weight (adjusted hazard ratio, 1.97; 95% confidence interval, 1.17-3.33). In female patients, the fitted association was inverse, without evidence of nonlinearity (P for overall association=0.030; P for nonlinearity=0.302). Obesity class I was associated with lower mortality than normal weight (adjusted hazard ratio, 0.24; 95% confidence interval, 0.08-0.73), although this estimate was based on few events. Conclusions: The association between body mass index and mortality after heart transplantation may differ by sex. The apparent lower mortality among female patients with obesity class I is hypothesis-generating and requires external validation.

Source: JHLT Open

DOI: 10.1016/j.jhlto.2026.100703