Simple tests used regularly to assess kidney function and damage also could help doctors predict who will develop heart disease, the nation's leading cause of death, researchers from Johns Hopkins Bloomberg School of Public Health have found.
The tests are just as good, if not better, than standard cholesterol and blood pressure tests, potentially giving doctors a better idea of which patients to more closely watch or treat, said Dr. Kunihiro Matsushita, an assistant scientist in the Baltimore school's department of epidemiology who led the research.
"Cholesterol levels and blood pressure tests are good indicators of cardiovascular risk, but they are not perfect," he said. "This study tells us we could do even better with information that oftentimes we are already collecting."
The tests assess kidney function by measuring a waste product in blood called creatinine and kidney damage by measuring a protein in urine called albumin.
The tests are frequently used because kidney disease is common (26 million people in the United States are affected) and because many professional associations as well as official government advisers recommend the tests to track people with diabetes and hypertension, as well as kidney disease.
The kidney function test, called "estimated glomerular filtration rate" or eGFR, is given 290 million times a year, the researchers said.
Matsushita says the finding could be used to develop calculators to spell out how much more risk different people of different nationalities and backgrounds face based on increases in creatinine and albumin levels. That way doctors would have a better handle on how much risk individuals have, particularly for heart failure, when blood isn't pumping normally; heart attack, when a clot blocks normal blood flow; or stroke, when a clot blocks blood flow to the brain.
They could prevent some death and disability by recommending medications or lifestyle changes such as increased exercise or improved diet, Matsushita says.
ORGANIC ASSOCIATION
Federal data show that every year in the United States more than 735,000 people have a heart attack and 610,000 people die of heart disease.
Only about half of those with heart disease have a classic indicator such as high blood pressure or high cholesterol, or are smokers, according the U.S. Centers for Disease Control and Prevention.
Researchers don't fully understand why there is such a strong association between kidney damage and risk of heart trouble. But they said those with chronic kidney disease have twice the chance of developing cardiovascular disease as those with healthy kidneys.
Researchers at Hopkins' Chronic Kidney Disease Prognosis Consortium analyzed data from 24 studies, including more than 637,000 people with no history of cardiovascular disease and the results of their kidney function and damage tests.
They found albumin specifically was a better predictor than standard tests in general, and an even stronger predictor in black Americans of African descent. Generally, the higher the albumin level, the higher the risk.
The tests are still not likely to be used on the general population to predict heart disease, said Dr. Josef Coresh, coordinator of the Hopkins kidney consortium and director of the Bloomberg School's G.W. Comstock Center for Public Health Research & Prevention.
The U.S. Preventive Services Task Force, which advises the government, doesn't recommend the tests for adults with no symptoms of kidney disease.
HIGHLIGHTING RISK
But some believe that the findings, published in May in the medical journal Lancet Diabetes and Endocrinology, support using the tests on people who are at risk of cardiovascular disease.
That would help doctors intervene "and save lives," said Dr. Leslie Spry, the medical director of the Dialysis Center of Lincoln in Lincoln, Neb., and a spokesman for the National Kidney Foundation.
More kidney patients die of heart maladies than wind up in end-stage kidney disease and on dialysis, but there hasn't been a way to predict which ones would have heart problems.
"In my 30 years of doing this, I've always felt people with kidney disease and protein in their urine were a different breed [from] people who don't have the protein," Spry said. "If you have the albumin, you have a greater chance of dying of heart disease. They've made the link."
He said more people should be advised to diet and exercise, quit smoking and even go on medications, he said. There also should be more trials to see if statins widely used to lower cholesterol in heart patients are safe for kidney patients.
Dr. Jeffrey Quartner, chief of cardiology at MedStar Union Memorial Hospital, agreed it would be helpful to know earlier who might develop potentially fatal heart problems. He said the kidney tests could serve as a "red flag" and could add to the overall evaluation of a patient. But he cautioned that it should not be the only test a doctor considers.
"The real take-home here is if you find there is damage to kidneys and the patient has not yet had anyone look at their heart function," he said, "they ought to be looked at."
ActiveStyle on 06/22/2015