P Pillay, A Mahomed, J Fabian
There was no significant association with post-liver-transplant mortality across BMI categories, except for class III obesity, which was positively associated. Owing to the limited number of participants with class III obesity, larger studies are needed to evaluate this further. The findings suggest that there is insufficient evidence to reliably use BMI as an exclusion criterion for liver transplantation, particularly for a BMI <40 kg/m2.
BACKGROUND: Uncertainty exists regarding associations between recipient pre-transplantation body mass index (BMI) and survival after liver transplantation, particularly in terms of obesity as an exclusion criterion. There are no studies assessing these associations in southern Africa, which has implications for the selection of potential transplant candidates in the setting of limited liver transplant availability.
OBJECTIVES: To determine associations between recipient pre-transplant BMI and survival after liver transplantation in Johannesburg, South Africa (SA).
METHODS: Adults aged ≥18 years who underwent liver transplantation for end-stage liver disease (ESLD) from August 2004 to January 2024 at Wits Donald Gordon Medical Centre were included in this cohort study. Multivariable Cox regression determined adjusted hazard ratios (HRs) and 95% confidence intervals (CIs), which were used for the associations of recipient pre-transplant BMI at listing and all-cause post-liver-transplant mortality. Survival at 1 and 5 years post transplantation was also assessed. BMI (kg/m2) was categorised using the World Health Organization classification: underweight <18.5; normal 18.5 - 24.9; overweight 25 - 29.9; obese: class I 30.0-34.9; class II 35.0 - 39.9; class III ≥40. Potential confounders adjusted for were age, sex, self-reported ethnicity, aetiology of ESLD, model for end-stage liver disease (MELD) score, ascites, diabetes, waitlist duration and postoperative complications. Effect modification by age, sex, self-reported ethnicity and MELD were assessed.
RESULTS: Among 489 adults, the median (interquartile range (IQR)) age was 53 (43 - 60) years; 290 (59.3%) were male; and in terms of ethnicity, 8 (1.6%) were Asian, 89 (18.4%) black, 35 (7.2%) Indian, 15 (3.1%) mixed and 338 (69.7%) white. Of these, 21 (4.3%) were underweight, 168 (34.4%) of normal BMI, 169 (34.6%) overweight, and 93 (19.0%) class I, 32 (6.5%) class II, and 6 (1.2%) class III obesity. After a median (IQR) of 5.3 (1.3 - 8.9) years follow-up, there were 187 (38.2%) deaths post liver transplantation. Using normal BMI as the reference category, there was no significant association with post-transplant mortality across BMI categories overall, except for class III obesity (HR 3.95; 95% CI 1.49 - 10.47). BMI was not significantly associated with 1- and 5-year post-transplant mortality.
CONCLUSION: There was no significant association with post-liver-transplant mortality across BMI categories, except for class III obesity, which was positively associated. Owing to the limited number of participants with class III obesity, larger studies are needed to evaluate this further. The findings suggest that there is insufficient evidence to reliably use BMI as an exclusion criterion for liver transplantation, particularly for a BMI <40 kg/m2.