Nonlinear Relationship Between Body Mass Index and Liver Transplant Outcomes: A Dose-Response Meta-Analysis.

Abstract

Background: Weight management was recommended to have more access to transplantation and improve transplant outcomes after liver transplantation (LT). However, the dose-response relationship between body mass index (BMI) and transplant outcomes has not been clearly defined.

Methods: PubMed, Embase, Web of Science, and Cochrane Library databases were searched up to October 20th, 2019. Dose-response meta-analyses was conducted to establish the dose-response relationship pattern.

Results: Twenty-three observational studies were eligible. In the pair-wise analysis, compared with normal BMI, HRs in underweight, overweight, obesity-I, obesity-II, and obesity-III were 2.13, 0.96, 1.06, 1.36, and 1.97 for patient death, and 3.08, 1.02, 1.25, 1.58, and 2.90, for graft loss. In the dose-response analysis, U-shaped relationships were observed between BMI and both patient and graft survival (P < .001, P < .001). Referring to 17.5kg/m², the patient death risk decreased to 0.72 (95% CI: 0.62-0.84) in 27kg/m² and then increased to 1.44 (95% CI:1.09-1.90) in 28.7-42kg/m². Comparing to 17.5kg/m², individuals in 26.7-28.0kg/m² had the least risk of graft loss with HR of 0.62 (95% CI:0.48-0.80) and increased to 1.64 (95% CI:1.03-2.61) in 42kg/m². Subgroup analyses by age, sex, sample size, duration of follow-up, location, publication year, and study type presented similar results.

Conclusion: Underweight and severe obesity are associated with a significantly increased risk of graft loss and patient death after liver transplantation. Overweight, especially BMI of 26-28 kg/m², may have extra survival benefit. Weight management before liver transplantation may be necessary.