The Liver Transplant Comorbidity Index (LTCI): A composite index of ambulatory pre-LT factors to identify patients at increased risk of post-LT mortality

Background and Aims: Frailty is strongly associated with mortality after liver transplantation. However, national guidelines discourage its use as a sole reason to decline a patient for liver transplantation, as some frail patients have acceptable outcomes. We aimed to develop a composite index, the Liver Transplant Comorbidity Index (LTCI), integrating frailty and other comorbidities, as a risk factor for longer-term (3-year) posttransplant mortality. Approach and Results: This 8-center prospective Functional Assessment in Liver Transplantation (FrAILT) Study included adult recipients of a primary deceased donor liver transplant from 2012 to 2022. Frailty was measured using the Liver Frailty Index (LFI ≥4.5=frail). Other candidate variables included demographics, laboratories, and comorbidities. Cox proportional hazards regression with best subset selection was used to identify risk factors of 3-year posttransplant death. The final model was selected based on Akaike Information Criterion and clinical pragmatism. Of 1472 liver transplant recipients, 290 (20%) were frail. Three-year posttransplant mortality was higher in frail versus non-frail patients (13% vs. 8%; p =0.03). The final LTCI included 5 variables: frailty, coronary artery disease, HCC, renal dysfunction, and diabetes. Three-year posttransplant mortality in low-risk, moderate-risk, and high-risk LTCI groups was 93%, 87%, and 80%, respectively. In multivariable analysis, after adjusting for donor factors (age and donation after circulatory death), both moderate-risk (HR: 2.23, 95% CI: 1.46–3.40; p <0.001) and high-risk (HR: 2.78, 95% CI: 1.67–4.64; p <0.001) status were associated with 3-year posttransplant mortality. Conclusions: The LTCI, comprising 5 pretransplant clinical parameters, effectively identifies patients at increased risk of posttransplant mortality. By integrating frailty in the context of other comorbidities, the LTCI can help providers better weigh the relative transplant risks and benefits and standardize the selection of transplant candidates.