People who live the farthest from liver transplant centers may be less likely to get on a waiting list, and ultimately to get a liver, than those who live closer, according to a new U.S. study.

The findings illustrate some of the potential unintended consequences of centralizing medical resources for specialized care, according to the study's authors.

"When designing these systems, it's important to keep this geography issue (as) an important feature," Dr. David Goldberg told Reuters Health. "Otherwise, it could get lost."

Goldberg is the study's lead author from the Hospital of the University of Pennsylvania in Philadelphia.

He and his colleagues note in the Journal of the American Medical Association that centralizing healthcare is a way to control costs, concentrate expertise and limit differences in the quality of care between regions.

While those approaches may be efficient, any benefit could be offset by patients having to travel long distances to access the care, they point out.

To see whether distance to centralized care is connected to outcomes for patients, the researchers analyzed data on liver patients within the Department of Veterans Affairs (VA).

The VA has five liver transplant centers nationwide, but veterans with additional insurance, such as Medicare, can use other transplant centers.

The researchers analyzed VA liver transplant records from 2003 to 2010. Overall, they had data on 50,637 veterans who were potentially eligible for transplants. Some 6 percent were put on waiting lists for a new liver - about half of those at VA transplant centers.

Of the patients receiving care at VA hospitals within 100 miles of a VA transplant center, about 7 percent were waitlisted at the VA centers and about 10 percent were waitlisted at any center.

That compared to about 3 percent having been waitlisted at VA centers and about 5 percent waitlisted at any center when veterans were being treated more than 100 miles from the closest VA transplant center.

Once on a waiting list, those veterans who were living farther away from a transplant center were less likely to get transplants, too.

And the likelihood of a liver patient dying over a five-year period rose with distance.

For example, a veteran living within 25 miles of a VA transplant center had about a 63 percent chance of being alive five years later, compared to about a 60 percent chance among people living more than 100 miles from a VA transplant center.

Organ transplant programs are highly specialized and organically require centralization, the authors acknowledge. Doctors would want patients available after a liver transplant for close monitoring and visits up to several times a week, Goldberg said.

It's possible that people living farther away from the VA transplant centers are less likely to even be evaluated for transplants because of the long distance, the researchers suggest. Alternatively, it could be that the transplant cannot move forward because patients and their families can't or won't relocate closer to the centers.

"While this issue of centralizing care may have many potential positives by concentrating expertise in one area, there are these unintended consequences that need to be considered," Goldberg said.

The study is not intended to be an indictment of the VA's transplant system, he added. In fact, the VA has approved the creation of two new transplant centers.

"I think that is one thing the VA should be credited for," Goldberg said.