New risk tool to predict cardiovascular disease events after liver transplant

Liz Meszaros, MDLinx | July 15, 2017

Researchers have developed the first liver transplant-specific risk tool—the Cardiovascular Risk in Orthotopic Liver Transplantation (CAR-OLT) score—available in web and mobile applications, that allows clinicians to accurately assess cardiac risk in liver transplant candidates, according to a study published in the latest issue of the journal Hepatology.

Advertisement

Liver-transplant specific risk tool

The CAR-OLT score allows clinicians to accurately assess cardiac risk in liver transplant candidates.

Approximately one-third of liver transplant recipients will have a cardiovascular complication within the first year of a liver transplant. Patients who are hospitalized for a cardiovascular complication after a liver transplant have lower survival than those who do not have cardiovascular complications.

Currently, there are no preoperative risk assessment tools for clinicians to estimate the risk for these events after OLT, and physicians have resorted to using several risk tools developed for a non-liver transplant population.

“Knowing the patient’s risk is critical to help prevent the frequent cardiac complications that accompany liver transplant surgery and to determine which patients are likely to survive the transplant,” said Lisa VanWagner, MD, MSc, assistant professor of medicine and preventive medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, and a Northwestern Medicine physician.  

Therefore, Dr. VanWagner and colleagues sought to develop a point-based prediction model, the CVD-OLT risk score. They enrolled 1,024 patients aged 18 to 75 years who underwent first OLT in a tertiary-care teaching hospital between 2002 and 2011, and used 10 years of data from a comprehensive institutional database (the Northwestern Medicine Enterprise Data Warehouse) that also was linked to data from the national Organ Procurement and Transplantation Network.

Main outcome measures included major 1-year CVD complications, which included death from a CVD cause or hospitalization for a major CVD event such as myocardial infarction, revascularization, heart failure, atrial fibrillation, cardiac arrest, pulmonary embolism, and stroke.

Major CVD complications occurred in 32.1% of subjects. The variables included in this model per model optimization strategies included pre-operative age, sex, race, employment, education, history of hepatocellular carcinoma, diabetes, heart failure, atrial fibrillation, pulmonary hypertension, hypertension, and respiratory failure.

The CAR-OLT point-based score had a discriminative performance (C statistic=0.78, bias-corrected C statistic=0.77) that was superior to other published risk models for postoperative CVD morbidity and mortality. The CAR-OLT point-based score also demonstrated appropriate calibration (Hosmer-Lemeshow P=0.33).

“Identifying persons who are at highest risk may mean restricting transplantation so that we maximize the benefit of scarce donor organs to persons who have a lower risk of a cardiac event and are more likely to survive the stress of a liver transplant,” concluded Dr. VanWagner.

This work was supported by the National Institutes of Health grant 1 F32 HL116151-01 and the American Liver Foundation. VanWagner is currently supported by the National Institutes of Health's National Center for Advancing Translational Sciences, Grant Number KL2TR001424. The Northwestern Medicine Enterprise Data Warehouse is funded, in part, by the National Center for Advancing Translational Sciences of the NIH research grant UL1TR001422 to the Northwestern University Clinical and Translational Sciences Institute.

The web and mobile applications for the CAR-OLT score were developed in collaboration with the Northwestern University Behavioral Intervention Technology (BIT) Core Facility with funding supported by the Northwestern Medicine Division of Hepatology Research Fund. The web application can be found at www.carolt.us  and the mobile app can be downloaded through the Apple iTunes and Google Play stores.  

Advertisement