THURSDAY, March 3 (HealthDay News) -- Minorities have a significantly lower chance of getting a kidney transplant than whites do, claims a new study that calls for changes in the formula used to decide who gets which donated organs.

The research, conducted at the University of Washington in Seattle, found that once "waitlisted" for a needed kidney, white patients were 40 percent more likely to receive a transplant than blacks, Hispanics, Asians and others. Lack of health insurance, poverty and cultural barriers were partly to blame for the disparity, the researchers found.

"Unfortunately, the disparities that we describe largely mirror racial or ethnic disparities in general health care in the United States," said study author Dr. Yoshio Hall, a professor of medicine and a researcher at the Kidney Research Institute in the department of medicine at the University of Washington.

When he worked at a large public hospital, Hall said he saw many poor, non-white, underinsured kidney patients were unable to obtain transplants at all.

Kidney disease is caused by a combination of genetic factors and chronic illnesses such as diabetes or high blood pressure. The condition damages the ability of the kidneys to filter toxic substances from the blood, and in the final stage requires treatment with a dialysis machine if a transplant is not performed. Survival rates vary widely, depending on many factors including the donor organ quality and how soon a kidney patient receives it, according to experts.

About 23 million Americans had chronic kidney disease in 2004, according to the U.S. National Institutes of Health (NIH). More than 523,000 U.S. residents were receiving treatment for kidney disease at the end of 2007, mostly on dialysis, NIH data shows.

It took longer for members of minority groups to get on the waiting list for a kidney, most likely "because of socioeconomic factors," such as poverty and having no health insurance, the study found. To pay for treatment, a poor person in need of a transplant must get Medicaid or Medicare, which can take several months, Hall explained.

Language and cultural barriers contributed to transplant delays for Hispanics, Asians and Pacific Islanders, the study found.

Patients' medical, economic and social situations are evaluated and if they have other serious diseases or insufficient social support, they are unlikely to be deemed a suitable candidate for an organ, Hall noted.

Once on the waiting list, donor matching, based on blood type and other measures of compatibility to prevent the body from rejecting the organ, "plays a central role" in having a transplant performed, Hall added.

The study analyzed records of more than half a million people who began kidney dialysis between 1995 and 2006, obtained from the U.S. Renal Data System registry and the United Network for Organ Sharing Kidney Wait List.

U.S. Census Bureau data was used to determine patients' residence in high poverty locations, and areas where language barriers and cultural isolation exist.

The study called for changing the formula used to allocate donated kidneys, to help reduce the racial and ethnic disparities that were found.

Another major factor affecting kidney transplant availability is geographic location. The United States has 11 regions overseen by the United Network for Organ Sharing, and donated kidneys are almost always kept within the region of origin.

A New York City kidney transplant surgeon said the regional divisions pose major problems in places like New York or San Francisco that have long waiting periods.

"This is a huge pet peeve for us," said Dr. Sander Florman, director of the Recanati/Miller Transplantation Institute at Mount Sinai Hospital in New York City. "It's completely unfair." Noting that kidneys can last more than 36 hours when kept cold, he said there were no good medical reasons for keeping donated organs within certain geographic regions.

Minorities are at an additional disadvantage because the best matches for organ donation are family members or people in the same ethnic group, and most donors are white, Florman said. Minority group family members often have the same health problems that cause a patient's kidney disease, he noted.

The real problem is "there aren't enough kidneys" to meet patients' needs, said Florman. He called for more education to get people "to sign the back of their driver's license," a common way to donate organs.

About 7,000 kidneys are donated each year, a number that "stays flat, as the demand grows exponentially," as the population ages, Florman said. "Right now there are over 110,000 people waiting for a kidney, and most will never get one."

More information

For more on kidney transplants, go to the National Kidney Foundation.