Cardiovascular disease (CVD) patients and those at risk for CVD should consider getting blood and urine tests that can detect chronic kidney disease (CKD), according to a new American Heart Association Science Advisory.
"Screening for kidney disease is important for patients with CVD because kidney disease is a serious major risk factor for CVD," said Frank C. Brosius III, M.D., chair of the statement writing group. "The simple, easy-to-do tests are great resources for doctors of CVD patients and can be done along with other tests."
Up to 11 percent of adults in the United States are estimated to have CKD (reduced kidney function or kidney damage). Death from CVD is 10 to 30 times higher in dialysis patients than in the general population.
Researchers considered the Modification of Diet in Renal Disease (MDRD) equation to calculate glomerular filtration rate (GFR), the most accurate index method to determine kidney function. The MDRD equation comes from a 1993 study about the role of diet in kidney disease. The formula uses standard aspects from patient information such as age and gender to predict the presence of kidney disease. It also uses laboratory reports of the blood levels of creatinine, which is a byproduct of muscle deterioration and an internal indicator of kidney filtration. The MDRD equation can be applied to a single blood sample to accurately detect CKD in patients with heart disease, Brosius said.
The advisory also highlights the need for healthcare providers to routinely screen for CKD and encourages laboratories to report estimated kidney function using the MDRD formula in CVD patients. Many creatinine lab reports already use this equation as a part of the report.
Albuminuria, high levels of the protein albumin in the urine, another sign of kidney damage, is also associated with an increased risk for CVD. Screening should be included in the assessment of all CVD patients using the single urine test, Brosius said.
"Doctors should look for patients' kidney function using both the MDRD equation and albuminuria tests," said Brosius, a professor of internal medicine and physiology and division chief of nephrology at the University Michigan Hospital Medical System in Ann Arbor, Mich.
"If one or both tests indicate kidney disease, then patients are at high risk for progressive CVD."
The authors recommend combined screening for albuminuria and estimation of kidney function with the MDRD study equation for all adult CVD patients. This includes those with coronary artery disease or congestive heart failure as well as those with CVD risk factors such as diabetes and hypertension.
"Cardiovascular patients should ask their cardiologists about the non-invasive tests to screen for kidney disease," Brosius said. "Doctors should use this advisory as a reminder of the important connection between kidney disease and cardiovascular disease."
Co-writers are Thomas H. Hostetter, M.D.; Ellie Kelepouris, M.D.; Mark M. Mitsnefes, M.D.; Sharon M. Moe, M.D.; Michael A. Moore, M.D.; Grace L. Smith, M.P.H; Subramaniam Pennathur, M.D.; and Peter W. F. Wilson, M.D.
Editor's Note: Online calculators for MDRD equations are available from the National Kidney Foundation at www.kidney.org and the National Kidney Disease Education Program (NKDEP) at www.nkdep.nih.gov.