Black people are much less likely than white people to be referred for kidney transplants, a new Harvard Medical School (HMS) study has found.

The study, one of many recent efforts to investigate the racial health care gap, found that white people with kidney failure were about 4 percent more likely to want a transplant than are black people. But black people were more than 20 percent less likely to be referred for evaluation and placement on a transplant wait-list.

The study also found that many doctors failed to inform black patients about the possibility of receiving a kidney from a family member instead of going on a wait-list.

One of the study's authors said poor doctor-patient communication is probably largely to blame for the discrepancy.

White doctors are more able to communicate with patients who are "closer to them culturally," said Dr. John Z. Ayanian, assistant professor of medicine and health care policy at HMS.

"We need to encourage physicians and patients to have more thorough discussions," he said.

Health Care Financing Administration (HCFA) officials announced last week that they will step up enforcement of existing rules against racial bias in kidney transplants.

HCFA, the federal agency that runs Medicare, Medicaid and various children's health programs, covers most dialysis and transplant costs for patients of all ages who lack private insurance.