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The newspaper of The Johns Hopkins University December 10, 2007 | Vol. 37 No. 14
SPH Study: Chronic Kidney Disease Now Common in the United States

Obesity, hypertension, diabetes, aging population contribute to increase

By Tim Parsons
School of Public Health

There is a high prevalence of chronic kidney disease in the United States, which has risen over the past decade, according to a study led by researchers at the Johns Hopkins Bloomberg School of Public Health.

The study found that the overall prevalence of chronic kidney disease increased from 10 percent of the population during a period from 1988 to 1994 to 13 percent from 1999 to 2004. The researchers conclude that the increase is partly due to the rise in the number of Americans with diabetes and hypertension and the aging of the population. The study is published in a recent edition of JAMA.

Chronic kidney disease increases the risk for complications from medications cleared by the kidney, hypertension, anemia, bone disease, death from cardiovascular disease and ultimately kidney failure, which requires treatment with kidney transplantation or dialysis.

"Our study demonstrates chronic kidney disease in the United States is more common than previously appreciated. However, less than one in 10 individuals with kidney disease are aware they have a problem," said Josef Coresh, lead author of the study and a professor in the departments of Epidemiology and Medicine at Johns Hopkins. "The medical community is starting to realize that chronic kidney disease is a serious concern, similar to the increased awareness of hypertension in the 1970s and diabetes in the 1990s."

Analyzing data from more than 28,000 participants in the National Health and Nutrition Examination Surveys for 1988-94 and 1999-2004, the research team measured the prevalence of chronic kidney disease stages 1 to 4. According to the results, the number of people with chronic kidney disease stages 1 and 2, those with increased protein in the urine but unimpaired kidney filtration, increased slightly from 4.4 percent during 1988-94 to 5 percent during 1999-2004. Larger increases were seen in the prevalence of stages 3 and 4 kidney disease, which indicate impaired kidney function called glomerular filtration rate; a GFR less than 60 equals approximately half the kidney function of young adults. The proportion of adults with this level of impaired kidney function rose from 5.6 percent to 8 percent.

The increases in prevalence of chronic kidney disease were largely due to the increases in the prevalence of diabetes, hypertension and obesity, as well as to the aging of the U.S. population. Some of the increase was due to a shift in the mean serum creatinine of the population, which is the blood marker of impaired kidney function.

"Americans and their physicians should be aware that chronic kidney disease is common, has treatable components and [that] its progression can be slowed substantially," said co-author Andrew S. Levey, chief of nephrology at Tufts-New England Medical Center. "Blood pressure control with agents that protect the kidney, blood sugar control and avoiding medications toxic to the kidneys are the most important factors for patients with kidney disease to be educated about."

The study was written by Coresh, Elizabeth Selvin, Lesley A. Stevens, Jane Manzi, John W. Kusek, Paul Eggers, Frederick Van Lente and Levey.

Funding for the research was provided by grants from the National Institute of Diabetes and Digestive and Kidney Diseases.


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