BALTIMORE, MD (ASRN.ORG)- Having both lungs replaced instead of just one is the single most important feature determining who lives longest after having a lung transplant, more than doubling an organ recipient's chances of extending their life by over a decade, a study by a team of transplant surgeons at Johns Hopkins shows.

The finding is potentially controversial, researchers say, because there is already a shortage of organ donors, and more widespread use of bilateral lung transplants could nearly halve the potential number of beneficiaries. Though more than 1,400 lung transplants occurred in the United States in 2008, another 2,000 Americans remain on lung waiting lists, while 80 more are waiting for both a heart and lung.

"Our results suggest that double-lung transplants have a long-term advantage, and surgeons should consider bilateral lung transplants whenever possible," says study senior investigator and transplant surgeon Ashish Shah, M.D. But, he notes, "Not all lung recipients necessarily need a bilateral transplant. Many people with chronic obstructive pulmonary disease, including emphysema and different kinds of pulmonary fibrosis, can survive with just one lung being replaced, while other lung diseases, such as cystic fibrosis, usually require transplantation of both lungs. But double-lung transplants clearly perform better over time.

"What we're really after here is to find as many factors as possible that support long-term survival, so that we maximize the gains in average lifespan for all our patients," says Shah.

Among the team's other key findings, to be presented April 22 in Paris at the 29th annual meeting of the International Society for Heart & Lung Transplantation, are that a perfect or near perfect match between the donor's immune-activating protein antigens with a recipient