Historically, it has been difficult, if not impossible, to accurately quantify the risk of accepting a deceased-donor kidney that may have been infected by hepatitis C, as compared to waiting what could be months or years for a better kidney. There is a 5 to 15 percent chance of dying every year on the waiting list. Often, kidneys that may have been at risk of infection are thrown away and never transplanted. In a new study in the American Journal of Transplantation, researchers showed there are some types of patients for whom survival benefit outweighs the risks of accepting a possibly infected kidney. They then developed a Web-based mathematical model to help predict which patients they would be. The easy-to-use website can be found at http://www.transplantmodels.com/ird.
Due to the fact that the supply of the healthiest donor kidneys is too small, patients need to consider all kidney offers or risk dying while waiting for a kidney. This is a very hard decision, and many people turn down kidney transplant offers that, in reality, would provide them significant benefit. Often they would have done much better taking the kidney at hand than waiting for the next available one. This is the most important decision of a kidney transplant candidate's life, a novel tool has been developed which can help patients make the best choice.
Before they are made available for transplant, kidneys from deceased donors (cadavers) are tested for infectious diseases such as HIV and hepatitis C. However, even when the tests come back negative, there is still a chance that some kidneys could be infected, more commonly with hepatitis C, because of donor risks such as intravenous drug abuse, prostitution, imprisonment and other criteria established by the U.S. Centers for Disease Control and Prevention. Although the risk of transmission of hepatitis C is low for transplanted kidneys, more than 10 percent of deceased donors in 2011 met the CDC criteria for infectious risk.
The researchers considered how long patients had been on a waiting list, whether they had undergone previous transplants, their age and whether they had diabetes, among other factors. Finally, they developed a complex statistical model and computer program to take all the factors into account and present it in a user-friendly manner. There are more than 102,000 people on the kidney transplant waiting list in the United States, and thousands will die before they get a kidney. The average waiting time for a kidney is three to five years, but in some regions of the United States, it can be as long as ten years. Some kidney transplant patients are healthy enough to safely reject a risky kidney and wait for a better one. But that is not always the case.
For example, a 45-year-old man who has been waiting two years for a new kidney, and thinks he has three more years to wait. Should he take an at-risk kidney, the Web-based tool says he would have a 78 percent chance of being alive in five years, even accounting for the possibility of an undetected infection such as hepatitis C. If he turns it down, his five-year survival is estimated to drop to 60 percent. It would make sense for this patient to take the kidney, because trying for a better kidney would likely result in a worse outcome. The story is different for a 25-year-old man who has been on the waiting list for four years, and possibly has one more year to wait. If he takes the risky kidney, he has an 84 percent chance of a five-year survival. The chance of a five-year survival is 83 percent if he waits for a better kidney to come along. In this example, it is not worth taking the risk of an infectious disease because you would do just as well with the next kidney without any risk of disease.
At the end of the day, this is a personal choice, and it is hard to know which kidney is the right one for you. As you can see this tool would make the decision easier, by clearly illustrating what is likely to happen depending on the choice you make.