NEW YORK, Oct 15 (Reuters) - For Alvin Roth, joint winner of the 2012 Nobel prize for economics, studying the economy is about finding real-life solutions for real-life questions and never more so than in a revolutionary new system to match kidney donors with patients.

Roth and fellow laureate, the mathematician, Lloyd Shapley, have seen their groundbreaking work used in such diverse areas as matching up employers with job seekers, doctors with residency programs, and students with schools.

But arguably its greatest impact has been matching kidney donors to patients in a system that was first applied in New England hospitals under the New England Program for Kidney Exchange (NEPKE), a scheme Roth helped found in 2004-2005.

The computerized pairing of groups of donors and patients that Roth’s models inspired has revolutionized the way kidney transplants are handled in the United States and has actually increased the possible number of transplants.

Throughout the United States nearly 2,000 patients have received kidneys under the system developed on Roth and Shapley’s models that would otherwise not have received them, according to Ruthanne Hanto, who has worked with Roth since 2005 after being co-opted to manage NEPKE.

In 2003, the year before the system was implemented, there were just 19 kidney transplants from live donors in the United States nationally, said Hanto. That number rose to 34 when the system was introduced in 2004. Last year it reached 443.

“The majority have been done with some kind of computer matching,” said Hanto, who is now project manager of the United Network for Organ Sharing (UNOS), a national kidney matching organization that NEPKE operations were folded into.

UNOS administers a kidney pared donor program for the Organ Procurement and Transplantation Network, a public-private partnership established in 1984 that links all of the professionals involved in the donation and transplantation system.

“He (Roth) had a hand in having these nearly 2000 transplants occurring in some form, because without his initial work none of the others would have been able to follow,” said Hanto.

Before wide-scale kidney-pair donations, donors and patients mostly worked through a single transplant center. A patient would identify friends and family that were willing to donate. But if those Kidney’s were not compatible with the patient the transplant could not take place and they would have to go on the waiting list for a deceased donor.

The system that Roth helped build uses complicated computer algorithms that allows patients to effectively swap incompatible donors with compatible ones from other donor-patient pairs. This can be done with single or multiple pares or in chains of unrelated donors and recipients.

Donors that were not used and were willing to donate to someone they did not know were also not lost to the system as they had been before, but could be matched up to other patients.

The system actually increases the number of kidney donations that are possible because it means that only people who really need deceased donors are given them while others are matched with live donors.

“Paired kidney donation is one of the few things that has happened in the recent decade or more that actually has come along and said we are going to get more kidney transplants into the system,” said Richard Formica, medical director of the kidney transplant program at Yale University.

Formica, who has worked on a committee called the kidney paired donation workgroup with Roth for about a year, says that with pared donations the number of transplants could rise from between 1,500 and 2,500 a year on top of the 15,000 transplants currently undertaken in the United States.

Formica also points out that because more people are able to have live donor transplants fewer have to return for second transplants as kidneys from live donor tend to last longer.

“His algorithm allows us to see combinations that you wouldn’t see,” said Formica. “It revolutionized the way we do it.”

Roth’s award is a reminder of kind of hands on work done by some economists that can often remain in the background while most of the attention focuses on economists who tackle the big, global policy issues du jour, such as eurozone debt crisis and the financial meltdown.

“Economics is about the real world,” Roth told Reuters shortly after finding out he had won the Nobel prize. “We are interested in how people lead their lives and like to think of economics as being not just a social science but a humanity.”

Roth works in a little known field known as market design that he affectionately describes as modeling the various “courtships” that occur when choice is not free, but depends on a second element in a pair.

Both Formica and Hanto describe Roth as a man who is both highly intelligent and good a describing his ideas in a way people can follow.

“Al is great to work with. Obviously he is highly intelligent, but very down to earth, which I think is a great combination,” said Hanto. “He is obviously very good at building a theory, but then taking that theory and putting into practice and looking at the practical implications of it.”

For Hanto, the challenge now is uniting the three national kidney pair donor systems into one unified system. (Editing by Andre Grenon)