Patients awaiting liver transplantation who also suffer from coronary disease, diabetes, chronic
obstructive pulmonary disease (COPD), connective tissue disease or renal insufficiency may face
poorer survival after liver transplantation. These conditions have been incorporated into a new modified
comorbidity index which helps predict post-transplant survival.

　Determining who receives the limited supply of donor organs is one of the greatest challenges facing
the transplant community. Severity of illness is the main criteria for hopeful liver recipients; however
it is not the only factor that influences post-transplant survival. In other medical fields, co-morbidities
have been considered as relevant predictors of survival, but never among the liver transplant
community.

　To address this paucity in the literature, researchers, led by Michael Volk, M.D., M.S. of the
Department of Gastroenterology at the University of Michigan Health System sought to determine if
the Charlson Comorbidity Index (CCI) would predict long-term survival after liver transplantation.

　They conducted a retrospective study of 624 patients who underwent liver transplantation at U-M
Hospital between 1994 and 2005 (to obtain a median follow-up of 5 years). They collected
demographic, clinical and laboratory data for each patient, but focused on the nine comorbidities
comprising the Charlson Comorbidity Index. These include congestive heart failure, coronary artery
disease, diabetes mellitus, peripheral vascular disease, cerebral vascular accident, COPD, connective
tissue disease, renal insufficiency and malignancy.

　Forty percent of the patients had one or more comorbidities prior to transplantation. After
statistical analysis, the researchers found that coronary disease, diabetes, COPD, connective tissue
disease, and renal insufficiency were all independent predictors of poorer post-transplant survival. The
researchers then recalibrated the CCI using this information, to create the CCI-OLT. This new index
predicted post-transplant survival equally as well as the other available model which uses recipient
characteristics like age, BMI, and etiology of liver disease.

　"Our study shows that comorbidities play an important role in determining post-transplant
survival," the authors report. "This information will be useful when counseling patients with
comorbidities about outcomes after transplantation."

　The study was limited by the fact that it was a single center, retrospective cohort study, and
the researchers were not able to determine to what extent the comorbidities were manifestations of
advanced liver disease. Still, the researchers demonstrated the usefulness of the modified comorbidity
index for predicting post-liver-transplant. "In the future, the addition of comorbidities to multivariable
models may be useful in developing new allocation algorithms which incorporate the likelihood of
post-transplant survival," they conclude.

　An accompanying editorial, by Richard Freeman of the New England Medical Center, lauds the
authors for their novel approach, though he cautioned that it remains to be seen if these results can be
replicated. He writes that it is also somewhat disappointing that the CCI-OLT index was no better at
predicting outcome than most of the other models already published.

　Still, he reports, the mathematical model presented by Volk and colleagues, "can help estimate ahead
of time what might be correct choices for patients when the call comes in the middle of the night."

　Article: "A modified Charlson Comorbidity Index for predicting survival after liver transplantation."
Volk; Michael; Hernandez, Jose; Lok, Anna; Marrero, Jorge. Liver Transplantation; November 2007.

　Editorial: "Predicting the Future?" Freeman, Richard. Liver Transplantation; November 2007.