The Regenerative Capacity of the Donor Liver After Living Donor Liver Transplantation: an Ambidirectional Cohort Study

Overview

Rationale: Living donor liver transplantation (LDLT) offers a promising solution to the organ shortage. During living liver donation, a substantial portion of the donor's liver is resected. Fortunately, the liver has a remarkable capacity to regenerate. However, liver regeneration varies among individuals. Previous studies have identified several clinical factors as potential predictors of regenerative capacity. Nevertheless, these studies are outdated and do not reflect current clinical practice or recent advancements. This study aims to investigate the regenerative capacity of the donor liver following LDLT and identify its clinical predictors. It is hypothesized that the liver regenerates to the original size. Objectives: The main objective of this study is to evaluate the regenerative capacity of the donor liver following LDLT. The secondary objective is to identify clinical predictors of the regenerative capacity of the donor liver following LDLT. Study type: This is an ambidirectional, single-center cohort study using medical records. Study population: The population consists of adult living liver donors aged 18-60 years at the Erasmus MC who donate(d) between May 2004 and June 2026 and gave written informed consent. Methods: General, graft weight and liver volumetry data will be extracted from HiX. The study coordinator will register his findings and analyze them. The paired samples t-test will be used to test for differences in mean remnant liver volume and liver volume 12 months post-donation. In addition, subgroup analyses will be performed for sex, age, weight, type of liver graft donation, anatomical variants, liver steatosis, and donor complications. Multiple linear regression analysis will be performed for sex, age, BMI, donor length of stay, remnant liver volume and percentage, and type of liver graft donation.

Research methods: General and graft weight data will be extracted from HiX. Additionally, liver volume pre-donation (VPRD) and 12 months post-donation (V12M) from CT- or MRI-volumetry will be extracted from HiX. The study coordinator will register his findings in Castor. Analysis: Normality will be tested using the Shapiro-Wilk test. Homogeneity of variances will be tested using the F-test. A QQ plot will be used to check for outliers. For the baseline donor characteristics, mean (standard deviation (SD)) age, weight, height, BMI, and the percentage of females and related donations, will be calculated. A table of these parameters will be made. The surgical outcomes OR time, blood loss, donor LOS, and Clavien-Dindo ≥III complications will be described and mean (SD) of these parameters will be calculated. A table of these parameters will be made. The mean (SD) remnant liver volume (RLV) and V12M will be calculated. The regenerative capacity will be calculated by the formula: regenerative capacity = V12M/RLV \* 100(%). For the mean regenerative capacity, the average of all donors' regenerative capacities will be taken. A table showing the means (SD) and min-max of RLV, V12M, and the regenerative capacities will be made. The distribution of regenerative capacities will be shown in a bar chart. The paired samples t-test will be used to test for differences in mean RLV and liver volume 12 months post-donation (V12M). In addition, subgroup analyses will be performed for sex, age (\<40 vs ≥40 years), weight (\<70 vs ≥70 kg), type of liver graft donation (right vs left lobe), anatomical variants, liver steatosis, and donor complications using the unpaired samples t-test, Welch's t-test, or Mann-Whitney test. Multiple linear regression analysis will be performed for the following 7 potential predictors of regenerative capacity: sex, age, BMI, donor LOS, remnant liver volume and percentage, and type of liver graft donation (right vs left lobe). Variance inflation factor (VIF) will be used to test for multicollinearity. Statistical analyses will be carried out using RStudio 2024.09.1, GraphPad Prism 9.5.0, and Microsoft Excel version 16.90.2. P\<0.05 indicates statistical significance. Recruitment and informed consent procedures: The transplant coordinator and/or transplant surgeon will inform participants about the study and will ask their written informed consent. Living liver donors are followed up annually for life. The participants will be informed during a follow-up consult. All donors who are, for whatever reason, not visiting the Erasmus MC anymore for follow-up are contacted by phone. If the donor considers participating, a Patient Information Form (PIF) will be sent by mail. The donors can return the signed PIF through mail. Donors can withdraw their informed consent at any time and for any reason if they wish to do so without any consequences. They can withdraw through phone, mail, or in person. Privacy protection: Subject's privacy is protected by using coded data. In the database subjects are referred to as numbers. These numbers are chosen at random. Which number belongs to which subject is registered in a key table with a password. This password is only known by the principal investigator and the research team. The database in which the data is stored (Castor), meets the requirements set for data security. The handling of personal data is in compliance with the Dutch Data Protection Act (in Dutch: 'Algemene Verordening Gegevensbescherming (AVG)). Only the code number will be used for study documentation, progress reports, and research publications.