(149) Survival outcomes following liver transplantation for individuals with cystic fibrosis living in North America

Background: Liver disease affects approximately 10% of people with CF with about 5% experiencing severe cirrhosis and portal hypertension. Timing for liver transplant in CF is controversial and often similar parameters are used to prioritize people on the waiting list regardless of the underlying disease. However, the course of CF liver disease is unique and individuals with cirrhosis and portal hypertension can remain stable for years without transplantation making it challenging to select the optimal time for listing. There is little literature on outcomes following liver transplant in the CF population. The objectives of this study were to describe the characteristics and health outcomes for those who undergo liver transplant in North America.

Methods: Data from the Canadian CF Registry and US CF Foundation Patient Registry (CFFPR) supplemented with data from United Network for Organ Sharing (UNOS) were used. The US CFFPR was probabilistically linked to UNOS Liver data using LinkPlus software matching on name, birth date, sex, and zip code. A cohort of individuals who underwent a liver transplant between 1987 and 2019 were included. Liver-lung transplant were excluded. Type of organ donor (cadaveric vs. living donor), time on waitlist and deaths on waitlist were calculated by donor type. Linear regression analyses were used to investigate trends over time with a Davies’ Test to find change points in trends. Time to death after liver transplant was calculated from transplant to date of death. Individuals were censored at December 31st of their last year of follow-up. Median survival time post liver transplant as well as 1-, 3-, and 5-year survival probabilities were calculated using the Kaplan-Meier method.

Results: Between 1987 and 2019, there were a total of 431 liver transplant recipients (8.4% in Canada and 91.6% in the US). Two-thirds (61.7%) of recipients were male. The median age at transplant was 15.2 years (range 0.5-63.1) and 66% of transplants were done in people less than 18 years of age. The majority (68.4%) of donors were cadaveric with 13.2% living donors and 18.3% with unknown donor status. Median time on the waitlist was 0.4 years (IQR 0.1-1.0) years. Median lung function prior to liver transplant was 69.8% predicted (IQR 53.9-83.1; n=385), 20% were of underweight (BMI < 18.5 kg/m2 for adults or BMI percentile ≤ 12% for pediatrics), 42.5% had CFRD, 97% were pancreatic insufficient, and 51% were homozygous F508 del. The median age of liver transplant has been significantly increasing over time from an initial median age of 12.7 years to 16.8 in 2019 (β=0.13, p=0.035). Since the estimated change point of 1996, the percentage of liver transplants over time has been steadily and significantly decreasing down from 0.066% in 1996 to 0.036% in 2019 (β=0.001, p=0.00084). Median survival time after transplant was 13.7 years (95% CI 11.4-15.9). Overall probability of survival at 1-, 3- and 5-years was 88.1% (95% CI 85-91.2), 82.4% (95% CI 78.8-86.2), and 76.5% (95% CI 72.4-80.8) respectively. There was no statistical evidence of a difference in survival between males and females (Log-rank p-value=0.1).

Conclusions: Compared to lung transplants, liver transplantation in CF is less common and occurs more frequently in the pediatric population. There is a high chance of survival even at 5-years post-liver transplant. Further analysis will be conducted to examine the impact of cadaveric vs. living donor on outcomes for NACFC.

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