Anemia and other conditions related to chronic kidney disease are independently associated with the risk of cardiovascular disease; conversely, heart disease is associated with a decline in kidney function and the development of kidney disease, according to two reports in the June 11 issue1 of Archives of Internal Medicine, one of the JAMA/Archives journals.
Chronic kidney disease is becoming increasingly prevalent in the
In one study, Peter A. McCullough, M.D., M.P.H., of
- estimated glomerular filtration rates (eGFR), or the rate at which kidneys filter blood, calculated based on levels of the waste product creatinine in the blood
- anemia, determined by blood hemoglobin levels
- and microalbuminuria, or slightly high levels (20 milligrams per liter or more) of the protein albumin in the urine
Of the participants who were followed for a maximum of 47.5 months, 5,504 (14.8 percent) had eGFR values of less than 60 milliliters per minute per 1.73 square meters, which were considered abnormal and signs of declining kidney function. In addition, 4,588 (13.1 percent) had anemia; and 15,959 (49.5 percent) had microalbuminuria. A total of 1,835 (4.9 percent) had a history of heart attack, 1,336 (3.6 percent) had a history of stroke and 2,897 (7.8 percent) had a self-reported history of heart attack or stroke.
Each of the three variables-anemia, microalbuminuria and low eGFR-was associated with cardiovascular disease. More than one-fourth of the patients who had all three kidney disease measures had cardiovascular disease, and their survival rates over the course of the study were lower by approximately 93 percent than those of any other group.
"These data suggest that screening for cardiovascular disease would be of high yield among patients with these risk markers but who do not report any history of cardiovascular disease symptoms," the authors conclude.
In a related study, Essam F. Elsayed, M.D., of
At the beginning of the studies, 1,787 (12.9 percent) of the participants had cardiovascular disease. As measured by creatinine levels, 520 individuals (3.8 percent) experienced a decline in kidney function-including 128 (7.2 percent) of those with cardiovascular disease and 392 (3.3 percent) of those without cardiovascular disease-and 314 (2.3 percent) developed kidney disease. The presence of cardiovascular disease at the beginning of the study was associated with a decline in kidney function and the development of kidney disease as measured by both creatinine levels and eGFR.
"Our study demonstrates that cardiovascular disease is associated with subsequent kidney function decline and development of kidney disease," the authors conclude. "This study identifies a population that may benefit from (1) increased cardiovascular disease risk factor surveillance and intervention, (2) heightened awareness of the risk factors associated with kidney disease, and (3) greater attention to and treatment for sequelae of kidney disease."
"Because these patients are mainly under the care of primary care physicians and cardiologists, it is important to draw attention to the increased risk of kidney disease in this population, with goals of preventing further progression, managing sequelae of kidney disease as they arise and adequately preparing individuals for kidney failure with timely nephrology referrals. Only with recognition of risk factors for kidney disease can this happen."
In an accompanying editorial in the journal2, Barry I. Freedman, M.D., and Thomas D. DuBose Jr., M.D., of the Wake Forest University School of Medicine, Winston-Salem, N.C., note that the presence of cardiovascular disease should now be recognized as a risk factor for the development of kidney disease, and patients with both should be screened and treated accordingly.
These two reports "address the interactive effects of kidney disease and cardiovascular disease risk in more than 50,000 subjects," they write. "These studies provide novel insights into the relationship between kidney disease and the vasculature."
"The chances for reducing the current high rates of chronic kidney disease and cardiovascular disease will be maximized when primary care physicians, nephrologists and cardiologists work in partnership to reduce and treat modifiable vascular disease risk factors, including those that are a consequence of kidney disease," Drs. Freedman and DuBose conclude.
"In addition, the potential for achieving current treatment goals in individuals at risk for nephropathy and cardiovascular disease using a more focused approach promises greater reductions in future cardiovascular disease and end-stage renal disease events."
1. (Arch Intern Med. 2007;167:1122-1129, 1130-1136.)
2. (Arch Intern Med. 2007;167:1122-1129, 1130-1136.)