Study leads to new heart transplant decision support toolFeb. 18, 2016, 9:10 AM
Because donor organs are scarce, understanding the mortality risk associated with heart transplantation is an important consideration when evaluating patients for transplant.
A recent study reported in JACC: Heart Failure has resulted in the development of a risk index tool to help clinicians accurately predict one-year mortality for patients on mechanical circulatory support, such as a left ventricular assist device (LVAD), which often serves as a bridge to transplant.
“In the past, patients waiting for transplant were sick and getting sicker while waiting. This created an urgency to use whatever organ becomes available. Now LVADs allow for stability and even better survival than an ill-advised transplant with a poor organ for that patient,” said Ashish Shah, M.D., senior author of the study. “As a result, the question of whether to accept a given donor offer may not be straightforward.”
Using the large United Network for Organ Sharing (UNOS) database, Shah and colleagues from other institutions created a decision support tool to help clinicians minimize and mitigate that risk and allow them to make informed decisions whether a donor heart is going to be a good match for a particular recipient.
UNOS captures all transplantations in the United States since October 1987. The study examined all primary orthotic heart transplant patients age 18 and older who underwent transplantation after 2000. The sample was then randomly divided into an 80 percent model derivation cohort and 20 percent validation cohort.
“We were able to look at thousands of patients and see what predictors of mortality were after transplant, and then based on how important those predictors were, we assigned a score to the derivation cohort and tested whether they worked against the validation cohort,” said Shah, professor of Cardiac Surgery and surgical director of Vanderbilt Heart Transplant and Mechanical Circulatory Support.
At least 20 variables were modestly associated with one-year mortality after transplant. For organ recipients, those included age, body mass index, intensive care unit admission, need for preoperative mechanical ventilation, renal and hepatic function, recent infection and type of support device.
Donor variables included donor age, sex mismatch with the recipient, ischemic time and donor kidney function.
Scores ranged from zero to 60, and each point increased the one-year odds of death by 8.5 percent.
The transplantation risk index is important in that it adds to the conversation about how to tailor the donor organs with recipients in order to maximize outcomes, Shah said.
“In the first study to model one-year mortality risk in patients bridging with MCS to transplant, we found that this simple additive score accurately predicted risk for one-year mortality after transplantation,” the authors concluded.