Kidney Disease Research Updates

Kidney Disease Awareness Low, Prevalence Remains High

Finding Underscores Importance of Campaign

Fewer than one in 10 Americans with poor kidney function are aware of their weak or failing kidneys, according to a new analysis of statistics from the Centers for Disease Control and Prevention, or CDC, and women are significantly less likely to be aware of the problem than men.

The research, part of an examination of data from the 1999 to 2000 National Health and Nutrition Examination Surveys, or NHANES, conducted by the CDC’s National Center for Health Statistics, found that the overall rate of chronic kidney disease was 9.4 percent, little changed since it was assessed at 8.8 percent by NHANES in 1988 to 1994 data.

By that estimate, almost 19 million Americans have kidney disease, and the low level of awareness underscores the importance of campaigns to raise awareness, according to Josef Coresh, M.D., Ph.D., the Johns Hopkins Bloomberg School of Public Health professor who led the effort.

Common Terminology
“Clearly, awareness in high-risk populations needs to be addressed and needs to be improved,” said Coresh, whose team included other Hopkins researchers and officials from the CDC and the National Institute of Diabetes and Digestive and Kidney Diseases, or NIDDK. Coresh said the low awareness may reflect that researchers have only just begun to agree on common terminology to describe kidney disease. “With kidney disease we are now probably where we were with hypertension 30 years ago.”

The government’s Healthy People 2010 program aims for significant drops in the number of patients with end-stage renal disease, untreated kidney disease, and the number of patients suffering complications as a result of kidney disease. The authors of the analysis said that their work underscores the importance of awareness and treatment campaigns in meeting the goals.

Emphasis on GFR
Public health officials said physicians can help boost awareness by moving away from reliance on creatinine levels alone to look for kidney disease. While creatinine remains a widely used marker of kidney health, Thomas Hostetter, M.D., an author on the study and the head of the NIDDK’s National Kidney Disease Education Program, or NKDEP, said that age, gender, race, and glomerular filtration rate, or GFR, should also be considered when assessing kidney function.

“This [study] emphasizes that laboratories need to do the GFR calculation,” said Hostetter, who suggests use of a GFR calculator on NKDEP’s web site: www.nkdep.nih.gov/professionals/gfr_calculators/index.htm. “A lot of people surveyed never knew that they had a kidney problem.”

Difference Between Sexes
The lack of widespread GFR use may also explain why the study found women were significantly less aware of kidney problems than men. The GFR calculation in women is different from the calculation used in men because kidneys in women tend to work at a different rate than in men, and a failure to take sex into account means that women with weak kidneys could be missed in routine screening.

Coresh said his team is interested in tracking the impact of kidney disease because of skyrocketing rates of patients requiring dialysis. The incidence of end-stage renal disease jumped by more than 50 percent between estimates drawn from the 1988 to 1994 data and the 1999 to 2000 numbers. The increase brings the number of Americans requiring a kidney transplant or dialysis to more than 400,000 and the price tag for treating such patients to $25 billion a year.

‘Tip of the Iceberg’
“We know that that’s only the tip of the iceberg. We’ve been trying to quantify the impact of the disease in the population at all stages,” Coresh said. Though mild to moderate kidney disease was once accorded less attention than when the disease is severe enough to require dialysis or transplantation, he said increasing attention is being paid to the link between kidney disease and other disorders, including anemia and cardiovascular disease.

The research team, writing in the Journal of the American Society of Nephrology, said the discrepancy between the little-changed kidney disease incidence and the rapidly growing end-stage renal disease rate was “surprising,” suggesting an increase in treatment rates, a higher rate of progression from kidney disease to renal failure, a drop in mortality from other causes, or a combination of these factors.

The study compared data on 4,101 patients surveyed in 1999 and 2000 with information on 15,488 patients collected between 1988 and 1994.

NIH Publication No. 06–4531
October 2005