How a patient will fare after an organ transplant can be difficult to predict. However, researchers using a computerized algorithm found that larger transplant centers have better patient outcomes than smaller centers. The results of their study were published recently in The American Journal of Transplantation.

Prior research studies have found an increased mortality rate among centers that perform fewer than 14 heart transplants or 20 lung transplants per year.

"The reason we did the simulation is because there is a lot of uncertainty in predicting post-transplantation outcomes," said Dr. Trent Magruder, a surgery resident and fellow in the Division of Cardiac Surgery at the Johns Hopkins University School of Medicine. "We hope our model will help illuminate areas for improvement and bring better and more predictable outcomes to doctors and patients."

This study used data from the United Network for Organ Sharing registry to predict whether thoracic transplant outcomes could be improved by sending patients from low-volume centers to higher-volume centers. Low-volume centers were defined as those that performed less than an average of 5.9 heart transplants or 11.9 lung transplants per year.

To create the model, researchers used information from 12,594 heart transplant patients and 12,300 lung transplant patients at 67 transplant centers in the U.S.

The algorithm was set up to mirror the 11 geographic regions defined by UNOS. It essentially "closed" the center in each region that did the fewest transplants each year. Then, the patients from the "closed" transplant center were assigned the largest transplant center's mortality rate. The process was repeated until either five transplant centers were "closed" or there was only one left in a region.

The results of the analysis were enlightening. For heart transplant patients, the first, second, third, fourth and fifth closings resulted in saving 10.1, 37.5, 76.6, 120 and 240.3 lives at the one-year post-op mark. For lung patients, 29. 2, 78.2, 124.6, 202.5 and 240 lives were saved one year following transplant.

"The message to our patients is, yes, it is worth it to make the effort to come to experienced centers," said Dr. Ashish Shah, professor of Cardiac Surgery and surgical director of Vanderbilt Heart Transplant and Mechanical Circulatory Support.

"The questions we had to ask and to answer were very uncomfortable ones," Shah said. "But they were crucial policy questions: How many transplant programs do we really need for a given population area, and how many programs that exist would end up closing in order to provide the most benefit to patients?"

"The conclusion of the study showed that closing programs would benefit patients and save lives," he said. "It brings key issues to the forefront, including how to have a very sober and candid conversation about how to deliver thoracic transplant care in the U.S. and how to delve into the elements that experienced centers utilize that are providing best patient outcomes.

"It's really a policy discussion that goes beyond individual transplant centers. We are trying to contribute to the larger conversation about best practices, policy and healthcare."

The next step is to determine what the larger centers are doing differently from smaller centers that results in increased mortality. That way, guidelines can be created to help centers across the nation.

"The goal of this study is not to say we need to close small centers," said Dr. Christian Merlo, an associate professor of medicine at Johns Hopkins. "It is food for thought that we hope will spark conversation among our colleagues about the need for a set of best practices and ways to share that information across centers."