Black patients face higher death rates in early stages of kidney disease

May 19 2008

Black patients are more likely to die in the early stages of chronic kidney disease than whites, according to a new study by a Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed) researcher and his team that will be published in the July issue of the Journal of the American Society of Nephrology.

"Blacks with early stage kidney disease who were younger than age 65 had a 78 percent higher risk of death than whites," said Rajnish Mehrotra, M.D., the LA BioMed investigator who was the lead author of the study. "Our findings indicate the socio-economic factors of poverty, a lack of insurance and lower education rates may contribute to these higher death rates among blacks. Addressing these factors could improve survival rates for blacks in the early stages of kidney disease."

Previous research has documented that, in general, mortality rates for blacks without chronic kidney disease are persistently higher than those for whites. With late-stage chronic kidney disease, the trend is reversed and blacks have a survival advantage over whites. Hispanic patients also seem to have a survival advantage over whites in these situations.

Puzzled by this paradox, Dr. Mehrotra and his team, which included LA BioMed investigator Sharon Adler, M.D., set out to find an explanation. They assessed data from a total of 14,611 patients in the Third National Health and Nutrition Examination Survey (NHANESIII), a population-based survey representative of the community-dwelling population of the United States.

The investigators found that 2,892 of the individuals in the survey had chronic kidney disease, 1,127 of whom died during follow-up. Among those with early-stage disease who were younger than 65 years, blacks had a 78 percent higher risk of death compared with whites.

This elevated risk was significantly related to socioeconomic status and access to care. There was also a non-significant trend for higher mortality among Hispanics compared with whites.

Dr. Mehrotra and his team conclude that their findings may explain the lower mortality rates observed among blacks with advanced kidney disease. As a result of the higher risk for death in the early stage of chronic kidney disease, only healthier blacks are surviving and developing later stages of chronic kidney disease.

In addition, the study's results indicate that racial differences in the death rates of chronic kidney disease patients depend more on sociological factors than on biological ones. Poverty and lack of education and medical insurance in particular may contribute to the high death rates among black individuals.

"These data suggest that factors such as education, poverty, and lower probability of medical insurance may be more important in mediating the high risk for death among younger black individuals than are biologic differences," the authors write. "This, in turn, may help in prioritizing interventions aimed at reducing the disparities among younger black individuals with chronic kidney disease."