Survival Benefit of Living-Donor Liver Transplant

Abstract

Importance: Despite the acceptance of living-donor liver transplant (LDLT) as a lifesaving procedure for end-stage liver disease, it remains underused in the United States. Quantification of lifetime survival benefit and the Model for End-stage Liver Disease incorporating sodium levels (MELD-Na) score range at which benefit outweighs risk in LDLT is necessary to demonstrate its safety and effectiveness.

Objective: To assess the survival benefit, life-years saved, and the MELD-Na score at which that survival benefit was obtained for individuals who received an LDLT compared with that for individuals who remained on the wait list.

Design, setting, and participants: This case-control study was a retrospective, secondary analysis of the Scientific Registry of Transplant Recipients database of 119 275 US liver transplant candidates and recipients from January 1, 2012, to September 2, 2021. Liver transplant candidates aged 18 years or older who were assigned to the wait list (N = 116 455) or received LDLT (N = 2820) were included. Patients listed for retransplant or multiorgan transplant and those with prior kidney or liver transplants were excluded.

Exposures: Living-donor liver transplant vs remaining on the wait list.

Main outcomes and measures: The primary outcome of this study was life-years saved from receiving an LDLT. Secondary outcomes included 1-year relative mortality and risk, time to equal risk, time to equal survival, and the MELD-Na score at which that survival benefit was obtained for individuals who received an LDLT compared with that for individuals who remained on the wait list. MELD-Na score ranges from 6 to 40 and is well correlated with short-term survival. Higher MELD-Na scores (>20) are associated with an increased risk of death.

Results: The mean (SD) age of the 119 275 study participants was 55.1 (11.2) years, 63% were male, 0.9% were American Indian or Alaska Native, 4.3% were Asian, 8.2% were Black or African American, 15.8% were Hispanic or Latino, 0.2% were Native Hawaiian or Other Pacific Islander, and 70.2% were White. Mortality risk and survival models confirmed a significant survival benefit for patients receiving an LDLT who had a MELD-Na score of 11 or higher (adjusted hazard ratio, 0.64 [95% CI, 0.47-0.88]; P = .006). Living-donor liver transplant recipients gained an additional 13 to 17 life-years compared with patients who never received an LDLT.

Conclusions and relevance: An LDLT is associated with a substantial survival benefit to patients with end-stage liver disease even at MELD-Na scores as low as 11. The findings of this study suggest that the life-years gained are comparable to or greater than those conferred by any other lifesaving procedure or by a deceased-donor liver transplant. This study's findings challenge current perceptions regarding when LDLT survival benefit occurs.

Figure 1.. One-Year Mortality Risk Across Model for End-stage Liver Disease Incorporating Sodium Levels (MELD-Na) Score Categories for Patients Receiving a Living-Donor Liver Transplant vs Remaining on the Wait List, 2011-2021

Relative hazard ratios were calculated at 1 year on the wait list and after transplant across 5 MELD categories (scores 6-10, 11-13, 14-16, 17-19, and 20-26). One-year, unadjusted hazard ratios (A) and covariate-adjusted Cox proportional hazard ratios (B) were reported with 95% CIs and significance thresholds. Unadjusted hazard ratios were calculated by dividing the mortality rate of patients receiving a transplant by the mortality rate of waitlisted candidates. Adjusted hazard ratios were calculated with the Cox proportional hazard model and were adjusted for age at listing, sex, and primary diagnosis. ^aP < .01. ^bP < .05. ^cP < .001.

Figure 2.. Survival Advantage of Living-Donor Liver Transplant (LDLT) vs Remaining on the Wait List Across 5 Model for End-stage Liver Disease Incorporating Sodium Levels (MELD-Na) Score Categories

Survival probability curves were calculated for waitlisted candidates (WL) and patients receiving an LDLT (LD) across 5 MELD score categories with the nonparametric Kaplan-Meier estimation. Time to equal risk (ER) was reported as the day at which transplant survival probability intersected wait list survival probability. Time to equal survival (ES) was reported as the day at which the cumulative areas under the curves were equal. All LDLT survival curves were statistically significant (P < .001) compared with those for the wait list.

Figure 3.. Life-Years Saved After Living-Donor Liver Transplant

Life-years from transplant (LYFT) were calculated for Model for End-stage Liver Disease incorporating sodium levels (MELD-Na) groups with scores below 20 using parametric survival regression and extrapolated to 10 000 days, or 27.38 years. The MELD-Na score category of 20 to 26 was excluded from this analysis because this group was underpowered. The overall projected survival benefit, or life-years saved, was calculated by subtracting the median number of days on the wait list from life-years from transplant. The median life-years saved ranged from 13.2 to 17.6 years.