Stroke risk

Research points out need for better treatment for kidney disease

Patients with chronic kidney disease (CKD) are at risk for stroke—regardless of whether they have high or low blood pressure, according to a Tufts study published in the March issue of the Journal of the American Society of Nephrology.

“Our study confirmed that individuals with CKD and elevated blood pressure are at increased risk of stroke,” said Dr. Daniel E. Weiner, assistant professor of medicine at Tufts. “Further, we found that individuals with the lowest systolic blood pressures and moderate kidney disease are also at risk of stroke—even compared to CKD patients with slightly higher blood pressure.”

Using data on more than 20,000 Americans participating in a long-term study of heart disease risk factors, the researchers looked at how CKD and blood pressure affect the risk of stroke. Based on a standard test of kidney function, 7.6 percent of subjects had CKD, a condition generally associated with progressive loss of kidney function. In addition to permanent loss of kidney function requiring dialysis or kidney transplantation, CKD has been linked to an increased risk of heart and blood vessel diseases.

At a follow-up of one year, just over five percent of CKD patients had a stroke. Compared to those without kidney disease, the stroke risk was 22 percent higher for CKD patients.

Stroke is one of the leading causes of death and disability in the United States. CKD is also extremely common—millions of Americans have kidney function in the range of the kidney disease population studied. The study was designed to address unanswered questions about the interplay between high blood pressure, kidney disease and stroke.

“This research points out how little we truly know about the best way to treat individuals with CKD,” Weiner said. Although the exact nature of the relationship among blood pressure, kidney disease and stroke risk is still unclear, the study results suggest several possibilities. “Most likely, low blood pressure identifies individuals with weak hearts or with stiff blood vessels that are unable to compensate to increase blood flow when needed or individuals who have a high pre-existing burden of vascular disease,” he said. “However, it is possible that low blood pressure itself may be directly harmful in patients with kidney disease due to decreased blood supply to the brain.”

This story ran in the Tufts Journal in May 2007.