Nearly 5 percent of those on the list died waiting and half again as many were stricken from the list because they'd become too sick to survive the procedure, according to the network.
A patient with Corbin's blood type can wait four to seven years for a transplant, Bromberg said. "That's quite a substantial amount of time for someone to be hanging out on dialysis waiting for an organ to be available," he said.
Corbin said her doctors urged her to switch to hemodialysis, which cleans a patient's blood directly and may be more effective. It can be done at home, but a helper is needed. Eddie, her husband, is partially disabled from a stroke, which ended his career as a waterman, at least for now, and also limits his ability to help.
She's tried hemodialysis before, however — when her replacement kidney first failed — and is not eager to return to it. Three times a week, she made the boat ride from Smith Island to the mainland and then drove to Salisbury to a dialysis center there. The treatment drained her strength as well as her blood, and all the travel added to her fatigue.
"By the time I'd rested up it was time to go back," she said.
Moving to the mainland to be closer to the dialysis center doesn't seem to be an option, either, since their income is limited. And it would mean leaving behind the close-knit network of family and island neighbors who help the Corbins out. Relatives carry the monthly shipments of dialysis supplies from the dock to their house, for instance.
"It's not easy living here, especially if you have to see a lot of doctors, like we do," she said. "But it's a good place to live. We know each other and depend on each other. We have lots of family here."
Family and friends have tried to find a donor, with appeals placed in local newspapers, on Facebook and circulated among church groups.
Despite a few responses, nothing has panned out.
"I had a man from Crisfield [call] that I didn't even know," Corbin said. "He'd seen our ad in the Crisfield Times. He was real excited. He wanted to give me a kidney."
Though he was the same blood type, his tissue didn't match. "He was so sad, I could tell when he called and gave me the bad news," she said.
Though Corbin doesn't complain much, Denny Bradshaw, who lives nearby, said his sister is "having a rough time of it. There's not many days she feels good."
Bradshaw, 62, said he's glad he was able to help his sister by giving her his kidney. She was not coping well with extended dialysis back then, either.
"It got down to the nitty gritty, something had to be done," he said. "Joan was going downhill fast. I just jumped in and did it."
Though hobbled by chronic back problems, he said he's had no complications from his act of generosity, nor any regrets.
"I don't know why there's not more donating kidneys," he said. "It's no big deal."
But for the recipient, he said, "It's a big thing. … You're saving somebody's life. It makes you feel like a hero."
Donors do fine with one kidney, medical experts say, in large part because doctors screen potential donors carefully to weed out any with underlying health problems or a family history of diabetes and other diseases that could weaken the remaining kidney.
Still, any surgical procedure comes with risks, advocates say. There also are other concerns, such as getting time off from work to recover and making sure health insurance coverage will not be affected.
Most transplanted kidneys come from people who've volunteered to donate them when they die — though for a variety of reasons those organs don't last as long as those from a living donor.
In Maryland, as in many other states, it's possible to sign up to be an organ donor either online or when getting or renewing a driver's license. There are no health or financial risks to discourage such generosity, as there may be with donating a kidney while alive. The number of such organ donor designations has risen nationwide, and about half of Maryland's licensed drivers have signed up.
But only 2 percent or 3 percent of those who've agreed to donate their organs die in circumstances that make it possible, said Jennifer Gelman with the Living Legacy Foundation, which handles Maryland's donor registry. For that reason, the foundation keeps campaigning to get more people to pledge to give the "gift of life" upon their death.
Corbin's doctors haven't told her how long she can continue on dialysis, and she hasn't asked.
"That's not something I want to know," she said. "I know after a time it weakens your heart, they did tell me that."
Despite it all, Corbin said she hasn't given up hope. She leans on the faith that runs strong in many islanders.
"A lot of people here depend on God, and he sees us through each challenge," she said. "That's what I've come to believe, and will always believe."