Kidney Disease Research Updates
Cholesterol a Poor Predictor of Heart Disease in Some Kidney Disease Patients
A new report from the African-American Study of Kidney Disease and Hypertension (AASK) helps explain the ambiguous relationship between cholesterol and cardiovascular disease (CVD) risk among people with moderate to severe chronic kidney disease (CKD). The study suggests health care providers also consider CKD patients’ weight and C-reactive protein—indicators of malnutrition and systemic inflammation—when assessing CVD risk.
Elevated cholesterol in people without kidney disease is a well-established risk factor for CVD. To reduce CVD risk, health care providers advise their patients to reduce cholesterol through dietary changes and medication. Studies supporting this clinical goal in patients with moderate to severe CKD, however, are inconclusive. While some studies demonstrate an association between cholesterol and CVD risk, others find no link.
Looking at data from the AASK, the researchers tested whether the presence of inflammation, malnutrition, or both changed the relationship between cholesterol and CVD risk. Inflammation was defined as having a C-reactive protein—a protein in the blood that increases in response to disease or infection—level above 10 milligrams per liter. Malnutrition was defined as a body mass index (BMI) of less than 23. BMI is an evaluation of a person’s weight in relation to height.
Supported in part by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the AASK is the largest study of CKD in African Americans. The study’s goals are to determine the underlying causes of CKD, which disproportionately affects African Americans, and find better ways to slow its progression.
Of the 990 participants with pre-dialysis CKD included in the analysis, 31 percent had either malnutrition or inflammation or both (M-I). During a 6-year period the occurrence of heart attack, stroke, death, or first hospitalization for coronary artery disease was similar to participants without M-I; however, elevated cholesterol was a risk factor only for the participants without M-I.
The finding indicates that while cholesterol is an important indicator of CVD risk, so too is M-I. “The pathogenesis of CVD in CKD is complex, with multiple risk factors contributing to the disease,” wrote Gabriel Contreras, M.D., associate professor of Medicine at the University of Miami Miller School of Medicine, and colleagues in their report published online September 23, 2010, in the Journal of the American Society of Nephrology.
The report argues for better clinical tools for predicting CVD risk in the CKD population, where M-I is present in up to 77 percent of patients. “Our study provides strong evidence that the equation development process should consider the role of M-I and potentially test separate equations based on the presence or absence of M-I,” Contreras and colleagues wrote.
The National Kidney and Urologic Diseases Information Clearinghouse, part of the NIDDK, has information about kidney disease. For more information, visit www.kidney.niddk.nih.gov.
NIH Publication No. 11–4531