More competition between medical centers that perform liver transplants may mean sicker patients get lower-quality donor organs, according to a U.S. study.

When more than one center has patients on the same donor list, the centers have an incentive to get organs for as many of their own patients as possible, wrote researchers, whose report appeared in Liver Transplantation.

So doctors are more likely to take the first available organ when their patient is at the top of the transplant list, whether or not that pairing has the best chance to succeed, rather than risk the organ will go to another center.

"There is the question whether competition decreases the ability of a center to better match donor and recipient characteristics," wrote John Paul Roberts, from the University of California, San Francisco, and colleagues.

They analyzed data on more than 38,000 liver recipients who had transplants from non-living donors between 2003 and 2009. The transplants were done at 112 medical centers in 47 so-called distribution areas - some covered by only one center and some that relayed organs to multiple transport centers.

Roberts and his colleagues found "clinically important differences" showing patients who received organs were initially worse off, with a higher risk of dying or having their transplant fail, in areas that had more medical centers in competition for the same organs.

For example, 10 percent of patients who received organs at centers with no competition had the worst scores for liver disease severity pre-transplant, compared to more than 28 percent of those in the high-competition distribution areas.

Areas with high competition also transplanted more organs that were considered at higher risk of failing, according to the new findings.

Although that might not be the best way of distributing organs on a society-wide scale, it could be considered a plus for the people who otherwise wouldn't get an organ or for livers that would otherwise be considered too low quality and be discarded.

"If you're a sick, high-risk patient... then it's in your interest that somebody will take more of a risk on you. The alternative is not surviving," said Michael Charlton, a liver disease researcher from the Mayo Clinic Transplant Center in Rochester, Minnesota.

Competition does increase access for patients, he said. So people who are very sick and turned away by a center that's the only place for transplants in its distribution area might have better luck elsewhere if they can afford to travel.

"The practice, in terms of choosing patients who can undergo liver transplantation and accepting organs that are already listed for transplantations, varies significantly between centers," said Charlton, who wasn't involved in the study, to Reuters Health.

But he cautioned that the way researchers measured competition - comparing the market shares for each transplant center in a given area - doesn't account for the effect of a center's reputation for good outcomes.

In that situation, a popular, higher-volume center would experience less competition from other centers and might also have better transplant records, so pure competition might not be the only explanation for outcomes.