TUESDAY, Jan. 27, 2004 (HealthDayNews) -- The puzzling paradox of people with high cholesterol levels appearing to be at a lower risk of death while on dialysis just isn't true, new research contends.
In fact, the three-year study shows that lowering cholesterol in this group would probably lower their risk of death even more.
Reporting in the Jan. 28 issue of the Journal of the American Medical Association, researchers from Johns Hopkins Bloomberg School of Public Health say, explain that malnutrition and inflammation -- two things prevalent in those who undergo dialysis -- raise the risk of mortality, but they can also lower cholesterol readings.
"Higher cholesterol is associated with a lower risk of mortality and cardiovascular risk in dialysis patients," says Dr. Josef Coresh, an associate professor of epidemiology, medicine and biostatistics at Johns Hopkins Bloomberg School of Public Health.
Coresh says the researchers thought something was probably masking the actual risk from high cholesterol.
"We did an assessment with three different tests. And once we took those into account, we saw that high cholesterol was a marker of overall and cardiovascular mortality," he says.
According to the National Kidney Foundation, about 275,000 people in the United States are currently on dialysis, a process that uses a machine to pull toxins from the blood when the kidneys can no longer do so on their own. Cardiovascular disease is rampant among people with end-stage renal disease, the study says, accounting for half of all deaths in those patients.
Coresh and his colleagues included 823 people who recently began undergoing dialysis at 79 centers across the United States. The study participants were between the ages of 18 and 95, with an average age of 57. Sixty-four percent were white and 30 percent were black. There were slightly more males than females enrolled in the study.
The researchers collected demographic information, as well as information on the study volunteers' condition at the start of the study. Then, an average of five months after the start of dialysis, blood samples were taken to measure cholesterol, inflammatory markers (C-reactive protein and interleukin-6), and albumin, a protein found in the blood that can be a marker of nutritional status.
During the nearly three-year study period, 324 study participants died; 159 of those deaths were from cardiovascular disease.
At first, Coresh says, it appeared that high cholesterol levels did lower the risk of mortality, but once the researchers factored in inflammation and malnutrition, higher cholesterol levels were associated with a more than 30 percent higher risk for overall mortality, and a 41 percent increase in risk for cardiovascular disease deaths.
Dr. David Goldfarb, director of dialysis at the New York VA Hospital, a says this is important research.
"That patients with high cholesterol had lower mortality and cardiovascular risk was always peculiar," he says. This study confirms that "having high cholesterol is not a good thing," says Goldfarb.
However, he adds, there's no proof that lowering cholesterol in this population will help.
He says that it probably will because people on dialysis have many cardiovascular risk factors, but that doctors are hesitant to prescribe additional medications to people on dialysis when there is no proven benefit.
In addition, he notes, because no one has really studied cholesterol-lowering medications in people on dialysis, it is unclear what their optimum cholesterol level should be. He says more studies need to be done to address these questions.
Echoing similar concerns about the cholesterol-lowering medications, Coresh says, "In many populations [they] show a strong benefit, but unfortunately, dialysis patients are often excluded from these trials."
Coresh says these findings may apply to other groups of sick people as well, such as smokers or people with heart failure, because malnutrition and inflammation can distort cholesterol findings.
More information
To learn more about kidney disease, go to the National Kidney Foundation. For more information on high cholesterol and tips for bringing it down, visit the National Heart, Lung, and Blood Institute.
