Study: Inflammation, malnutrition identified as key risk factors
By Eric Vohr
Johns Hopkins Medicine
In a 10-year study of more than a thousand kidney failure patients, sudden cardiac death emerged as the No. 1 cause of death for patients on dialysis, according to a Johns Hopkins researcher.
The study, already published online and appearing in the Nov. 2 issue of Kidney International, identified systemic inflammatory response and malnutrition as key risk factors for the fatal heart attacks.
"This is believed to be the first time anyone has taken a rigorous prospective look at why so many patients on dialysis die from sudden cardiac death, and the results could help doctors identify those at highest risk and potentially save lives," said Rulan S. Parekh, associate professor in the Department of Nephrology at the Johns Hopkins University School of Medicine.
Parekh and her team gathered their data from a cohort of 1,041 end-stage renal disease patients on dialysis who were part of Choices for Healthy Outcomes in Caring for ESRD, known as CHOICE. In a 9.5-year period, 658 of this group died. The largest number of these deaths, 146, was the result of sudden cardiac death, or SDC — in this case, unexpected deaths that occurred outside the hospital setting.
The researchers then looked at previously recorded blood test results from 122 of these 146 sudden cardiac death patients to search for a possible relationship between the deaths and levels of high-sensitivity C-reactive (hsCRP), interleukin-6 (IL-6) and albumin. The proteins IL-6 and hsCRP are both markers for widespread blood vessel and organ inflammation, while low albumin levels are associated with malnutrition.
Results showed that patients with high levels of either hsCRP or IL-6 were twice as likely to die from sudden cardiac death as those with low levels of these proteins. Low albumin levels were associated with a 1.35 times increase in the risk of dying of sudden cardiac death when compared with high levels, according to Parekh. In addition, those with low levels of albumin and high levels of hsCRP were four times more likely to die of sudden cardiac death than those with high levels of albumin and low levels of hsCRP.
"These results tell us that ESRD patients with low albumin and/or high levels of IL-6 and hsCRP are at a significantly higher risk of SCD," Parekh said.
The half-million people in the United States with ESRD are 10 to 100 times more likely than the general public to die from cardiovascular disease, depending on age, according to Parekh. They have an annual mortality rate of more than 20 percent, and one-fifth of these deaths are attributed to sudden cardiac death.
Systemic inflammatory response is common with ESRD patients and occurs when the body responds to an infectious or noninfectious attack. Parekh said that because those with kidney failure are quite ill, the chance of infection and chronic inflammation is higher. Also common with ESRD patients is malnutrition from the stress of kidney failure, loss of appetite and a highly restricted diet; compounding the issue, she said, is that Medicare does not cover oral nutritional supplements.
"When people think of heart attacks, they think of cholesterol and obesity," Parekh said, "but these are risk factors for hardening of the arteries and are not directly linked to sudden heart death among patients on dialysis."
Other researchers from Johns Hopkins who contributed to this study are Neil R. Powe, Josef Coresh, Lucy A. Meoni, Bernard G. Jaar and Nancy E. Fink, all of the School of Medicine; and Michael J. Klag, W.H. Linda Kao and Laura C. Plantinga, all of the Bloomberg School of Public Health.