Patients who underwent lung transplants lived an additional three years compared with patients who never received donor organs, even if the lungs they received came from people who had previously smoked, according to a new British study published in the Lancet.

Researchers led by Dr. Robert Bonser of University Hospital Birmingham analyzed how donor smoking history affected three-year survival using patients on the U.K.  Transplant Registry between 1999 and 2010.

About 39 percent of the 1,295 lung transplants used lungs from donors who'd previously smoked.  While the three-year survival rate for these transplant recipients was lower than for people who received lungs from nonsmokers and had more complications, survival was still better than for people who'd never had transplants at all.

Their findings, the authors wrote, support a policy of accepting lungs from people with smoking histories.

"Donors with positive smoking histories provide nearly 40 percent of the lungs available for transplantation," they wrote.  "Rejection of this donor-organ resource would increase waiting-list mortality and is ill advised.

In an accompanying editorial, Drs. Marcelo Cypel and Shaf Keshavjee of the Toronto Lung Transplant Program explained that the risks and benefits of lungs from donors who smoked varied by country and transplant center.

One way to increase the safety and efficacy of available lungs is through the use of techniques that can preserve and repair lungs damaged by certain diseases.

In the U.S., the United Network for Organ Sharing, which manages the country's organ transplant system, instituted  a lung allocation system designed to make better use of the few donated organs available and  to reduce the number of people who die while waiting for a transplant.

Each person on the waiting list is given a score indicating how severely ill the person is and how likely it is for a transplant to succeed.  The scores are used to determine priority once an organ becomes  available.

This program, Cypel and Keshavjee wrote, "reduced mortality of patients on the waiting list without a substantial increase in lung donors."

And while Bonser and his co-authors believe that lungs from donors who smoked shouldn't necessarily be rejected, they recommend that patients "be informed that the use of such lungs could reduce their lifetime."