Kidney Disease Increasing in U.S.

Mar. 23 --

TUESDAY, Nov. 6 (HealthDay News) -- The number of Americans with chronic kidney disease is on the rise, and diabetes and high blood pressure linked to obesity appear to account for most of the increase, a new study suggests.

"When we looked at how common kidney disease was, we found that it was more common than previously appreciated," said lead researcher Dr. Josef Coresh, a professor of epidemiology at Johns Hopkins University.

The prevalence of chronic kidney disease among U.S. adults has risen in a decade from 10 percent to 13 percent, according to the report in the Nov. 7 issue of the Journal of the American Medical Association.

The aging population is part of the reason for the increased prevalence of kidney disease, Coresh said. But, he added, "There are also substantially higher rates of obesity and diabetes. These are both risk factors for kidney disease."

In addition, more people have high blood pressure, which is often uncontrolled, Coresh noted. High blood pressure can also damage the kidneys.

For the study, Coresh's team collected data on 15,488 people in the 1988 to 1994 National Health and Nutrition Examination Surveys (NHANES). The researchers then compared these people with 13,233 people who participated in the 1999 to 2004 NHANES survey.

The researchers compared the levels of chronic kidney disease between the two groups. To establish the presence of kidney disease, Coresh's group used measures of excess protein in the urine and the glomerular filtration rate, which measures the amount of fluid filtered by the kidneys.

The prevalence of protein in urine and a reduction in the glomerular filtration rate both increased from the first to the second survey. Overall, the prevalence of chronic kidney disease increased from 10.0 percent in the 1988-to-1994 survey to 13.1 percent in 1999 to 2004 survey, the researchers found.

The increase in the prevalence of kidney disease appears due to more cases of high blood pressure and diabetes being diagnosed, and much of that is caused by obesity. This increase in obesity seems to explain the increase in extra protein in the urine but only part of the decrease in the glomerular filtration rate, Coresh said.

Chronic kidney disease increases the risk of heart disease as well as kidney failure and other complications. Currently, there are about 500,000 people with kidney failure who are treated by dialysis or transplantation in the United States, and that number is expected to increase to 750,000 by 2015, Coresh said.

"If diabetes continues to increase, and obesity continues to increase, then it stands to reason that the prevalence of kidney disease will continue to increase," he said.

Dr. Ajay Singh, chief of the renal division and director of dialysis at Brigham and Women's Hospital in Boston, thinks this study clearly shows the need for more research in preventing and treating chronic kidney disease.

"This data shows that the prevalence of kidney disease is increasing, and that it appears to reflect, at least in part, the increasing incidence of diabetes, high blood pressure, and obesity," said Singh, who's also an associate professor of medicine at Harvard Medical School.

The findings also underscore the importance of early recognition of kidney disease and the need for preventive strategies, Singh said. "Since current treatments only slow down kidney progression, more research dollars need to be allocated to understanding the reasons why kidney disease progresses and how we may be able to prevent it," he said.

More information

For more on kidney disease, visit the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.

SOURCES: Josef Coresh, M.D., Ph.D., professor of epidemiology, Johns Hopkins University, Baltimore; Ajay Singh, M.D., clinical chief, renal division, and director, dialysis, Brigham and Women's Hospital, and associate professor, medicine, Harvard Medical School, Boston; Nov. 7, 2007, Journal of the American Medical Association