Improving Access to Liver Transplantation: Scoring System for Waitlisted Liver Patients

Fakhar Ali Qazi Arisar - Multi Organ Transplant Program, University Health Network Mamatha Bhat - Multi Organ Transplant Program, University Health Network Wei Xu - Department of Biostatistics, Princess Margaret Cancer Center, University Health Network, Toronto

This Poster Pitch highlights the utility of living donor liver transplant for patients who are under-served by MELD scoring system.

DESCRIPTION
Liver transplantation has been offered to patients with end-stage liver disease with excellent overall survival. However, a growing waiting list has increased the demand for organs, while supply has not kept up. Therefore, waitlist mortality is as high as 25%. Current models of organ allocation depend on assessment of medical urgency for transplant and mortality on the waiting list using MELD and MELD-Na. These predictive models are based on objective laboratory parameters including bilirubin, INR, creatinine, and sodium. Kim et al 2008.

Although MELD and MELD-Na models are excellent predictors of waitlist mortality, there are few limitations. These models do not consider the degree of physical decompensation such as ascites, encephalopathy, sarcopenia and frailty. Moreover, the waitlist population has changed significantly over last decade. Kim et al 2018. Patients in the current era are sicker, older, have more comorbidities, and are less likely to be transplanted for viral hepatitis. Kim et al, 2018; Yang et al, 2017; Flemming et al 2017.

The performance of MELD and MELD-Na remain excellent, although it has worsened over time from 2005 to 2015. Asrani, 2020 Hence their performance in the current era is of concern. Furthermore, women are particularly disadvantaged by the MELD scoring system for various reasons, e.g. low muscle mass, small stature and serum creatinine not appropriately reflecting the renal dysfunction. Lai et al 2010; Allen et al 2018; Nephew et al, 2017.

In the setting of scarce deceased donor organs, living donor liver transplantation has emerged as a viable alternative. Access to LDLT shortens the waiting time and decreases waitlist mortality. We have found that in waitlisted patients with NASH cirrhosis, having a potential living donor was associated with a higher instantaneous rate of receiving a transplant, particularly for patients who were older than age 60, diabetic, with height less than 165 cm, and MELD Na less than 20.

We devised a preliminary scoring system taking into account these parameters to predict which of the NASH waitlist patients would especially benefit from access to living donation. We have separately found that access to LDLT particularly helps women as compared to men.

We would like to therefore validate our model among other underserved populations such as women and patients with PSC. We hypothesize that waitlisted patients with NASH cirrhosis, PSC cirrhosis or who are female would be advantaged by having access to LDLT, particularly if they are older, have systemic comorbidities and have some degree of frailty. Given that UHN's liver transplant program performs a significant number of both deceased donor liver transplant and living donor liver transplant, we are in the unique position of being able to examine the impact of access to living donation on waitlist outcomes in LT candidates.

Fine and Gray’s Competing risk models will be built to examine the effect of availability of pLD on cumulative incidence of transplant, while death will be treated as the competing risk event. Additionally, Machine Learning methodology will be employed to construct a scoring system that incorporates these competing risk models and various features. The developed risk score would help identifying the patients/features particularly benefitting from access to living donation, and will serve as a framework to particularly encourage living donation among patients currently underserved by the MELD Na score.

References

[driqbalalikhan]

Nicely detailed ...
Simple and accurate .