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 issue of Archives of Internal Medicine.
Chronic kidney disease is becoming increasingly prevalent in the United States and worldwide, according to background information in the articles. Chronic kidney disease is associated with a wide variety of complications, including anemia (low red blood cell count, or red blood cells that are deficient in oxygen-transporting hemoglobin), nerve pain, bone disease, death and cardiovascular disease. Most patients with chronic kidney disease die of complications from heart disease rather than of kidney failure.
In one study, Peter A. McCullough, M.D., M.P.H., of William Beaumont Hospital, Royal Oak, Mich., and colleagues assessed a group of 37,153 individuals who were screened for kidney disease through a community-based program between 2000 and 2003. The participants (average age of 52.9 years) all reported a personal or family history of diabetes, hypertension or kidney disease on a screening survey. Patients had their blood pressure measured and provided blood and urine samples, which were processed to assess three markers of chronic kidney disease:
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.