Validation of cardiovascular risk scores in a liver transplant population

Two methods of assessing a patient's risk of cardiovascular events - SCORE and PROCAM - proved more valuable for liver transplant recipients than an alternative method, according to a new study.

These findings are published in the March 2006 issue of Liver Transplantation, the official journal of the American Association for the Study of Liver Diseases (AASLD) and the International Liver Transplantation Society (ILTS). Published on behalf of the societies by John Wiley & Sons, Inc., the journal is available online via Wiley InterScience.

Patients who receive liver transplants often have an increased prevalence of cardiovascular risk factors, and cardiovascular events are a major source of their morbidity and mortality. Due to excellent long-term survival, there is an increasing emphasis on identifying transplant recipients at risk for immunosuppression-related late complications. Understanding each transplant recipient's risk for cardiovascular events is one important consideration.

In search of the best method of estimating a patient's risk of a cardiovascular event, researchers led by Dr. Olaf Guckelberger of the Department of General, Visceral and Transplantation Surgery at Chariti - Campus Vichow-Klinikum in Berlin, Germany, sought to identify relevant independent variables, as well as the algorithm that would most accurately quantify a transplant candidate's risk of future cardiovascular disease.

The researchers retrospectively studied 303 patients who had received a liver transplant between 1988 and 1994. They gathered clinical and demographic data at six months post-transplant, including age, gender, smoking-status, family history of cardiovascular disease, arterial blood pressure, height, weight, medication and serum levels of creatinine, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and glucose after fasting. They then used this data to calculate three established cardiovascular risk scores: the Framingham risk score (FRS), the German Prospective Cardiovascular M|nster Study (PROCAM), and the European Systematic Coronary Risk Evaluation Project (SCORE), all of which predict the 10-year-risk of coronary or cardiovascular events or fatalities. They compared the actual incidence of cardiovascular events, such as myocardial infarction and coronary heart disease, over 10 years post-transplant to better understand the predictive power of each score.

"In our liver transplant population at six months post-transplantation, PROCAM and SCORE provided an excellent measure to discriminate between patients at high or low risk for coronary events," the authors report. The Framingham risk score, however, did not identify high-risk liver transplant recipients as accurately.

In an editorial published in the same issue, Christopher P. Appleton, M.D. and colleagues of the Mayo Clinic confirm that assessing short and long term cardiovascular risk is an important aspect of pre-liver transplant evaluation, however, they suggest that the Framingham risk score does have some predictive power.

While they agree with Guckelberger's assertions that it is important to determine cardiovascular risk in patients in need of a liver transplant, the authors add, "The assertion that there are significant differences in the three global CV disease risk stratification algorithms studies is less certain." They suggest that aspects of the study--such as information about transplant patients who were not included--require further investigation.

Both groups of authors propose additional studies to validate the current findings before applying them to liver transplant populations. Appleton, et al., suggest future prospective studies that add newer reported risk factors to those previously established, including serum high sensitivity C-reactive protein, fibrinogen, homocysteine, lipoprotein and apolipoproteins A1 and B.