To understand the health effects of high cholesterol levels, doctors first need to assess malnutrition and inflammation status in their chronic kidney disease  patients, according to a study appearing in an upcoming issue of the Journal of the American Society of Nephrology.

Patients with chronic kidney disease often develop and die from cardiovascular disease. While it's well known that high cholesterol puts people at risk for cardiovascular disease in the general population, the relationship is not as clear in chronic kidney disease patients. In fact, research has shown that dialysis patients with higher cholesterol levels die at a lower rate than those with lower cholesterol levels. It's not that high cholesterol is beneficial; rather, the higher levels may indicate a lesser degree of malnutrition and inflammation, two serious and interrelated complications of kidney disease.

To see whether malnutrition or inflammation might modify the relationship of cholesterol and cardiovascular disease, Gabriel Contreras, M.D., M.P.H., professor of medicine at the Miller School, and Lawrence Appel, M.D., from Johns Hopkins University, and colleagues studied 990 African-Americans with hypertension and chronic kidney disease who were not yet on dialysis, 31 percent of whom had malnutrition and/or inflammation.

Over the course of 12 years, 20 percent of the patients experienced a new cardiovascular event such as heart attack, stroke, congestive heart failure, or death from heart disease, with similar numbers in the groups with 19 percent in the group with malnutrition or inflammation and 21 percent in the group without malnutrition or inflammation.

In the patients with malnutrition or inflammation, high blood cholesterol levels were not associated with cardiovascular events; however, in the patients without malnutrition or inflammation (69 percent), the patients' risk of developing a new cardiovascular event increased as cholesterol levels rose.

"In chronic kidney disease patients, the inconsistent and often inverse relationship of cholesterol levels with cardiovascular disease and overall mortality may be explained by the presence of malnutrition and inflammation," said Dr. Contreras. "Traditional risk factors such as elevated blood cholesterol levels remain important; however, they appear to compete and interact with non-traditional risk factors such as malnutrition and inflammation. Doctors caring for chronic kidney disease patients should take into account the presence of malnutrition and inflammation as they interpret blood cholesterol levels."

Malnutrition and inflammation complicate blood cholesterol readings in chronic kidney disease patients, making it important that physicians investigate the causes of high or low cholesterol in their patients.

The findings are part of the African-American Study of Kidney Disease and Hypertension funded by the National Institutes of Health.