More attention needed to results of simple test of kidney function
Kidney disease in the United States is both common and under-diagnosed, but two new studies led by Johns Hopkins Bloomberg School of Public Health researchers suggest that paying close attention to results of a simple blood test can help predict the likelihood that patients are headed for kidney failure or death.
The researchers from the Chronic Kidney Disease Prognosis Consortium, led by Josef Coresh, MD, the George W. Comstock Professor of Epidemiology at the Bloomberg School, say the findings emphasize how important it is that both doctors and patients keep an eye on measures of kidney function, including how they progress over time. The findings are published Dec. 11 in the Journal of the American Society of Nephrology.
"Patients and physicians should pay attention to the estimates of kidney function which are routinely obtained, but all-too-often ignored," says Coresh, who also directs the Bloomberg School's George W. Comstock Center for Public Health Research and Prevention. "It costs cents to do this test and it is done all the time. The results can inform treatment decisions that may be able to slow kidney function decline. And while the test is more informative to doctors than a glucose test for diabetes, the results are many times overlooked, particularly when a patient has other chronic illnesses that required more immediate consideration."
Researchers estimate that 10 percent of the U.S. population - more than 20 million people - has kidney disease and that less than one in five of those who have it are aware that they do.
The researchers analyzed data on more than 1.2 million subjects with and without kidney disease, more than 102,000 of whom died over a three-year study period. They primarily focused on the results of tests of the estimated glomerular filtration rate, eGFR, which is used to screen for and detect early kidney damage and to monitor kidney function. They looked at the most recent eGFR but also at test results over time in the same patients.
While they found that the most recent eGFR value was the most valuable when it came to predicting both kidney failure and mortality, looking at historical tests also provided information that could be useful to patients and physicians. Electronic medical records routinely found in many hospitals and physicians' offices should be useful in determining the trajectory of kidney function over time. Having this information not only informs prognosis, but can help doctors steer their patients toward treatments such as ACE inhibitors which can slow the decline in kidney function among patients with protein in their urine or away from non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen which can damage the kidneys.
"We have long known that the most recent screening of kidney function is a good indicator of kidney health, but this analysis tells us that the rate of past decline is also informative for both the risk of kidney failure and mortality," he says. "Computer systems should make it easier than ever before to calculate the rate at which kidney disease is progressing or whether it has stabilized. This information can inform physician and patient decisions about how to reduce future decline in kidney function."
Coresh also says doctors should be sure to follow up blood tests that suggest kidney disease with a test for protein in the urine, which is an excellent indicator of future kidney function decline, kidney failure and mortality.