Low Blood Pressure Ups Stroke Risk in Kidney Patients

Friday, February 23, 2007; 12:00 AM

FRIDAY, Feb. 23 (HealthDay News) -- Both low and high blood pressure increase the risk of stroke in people with chronic kidney disease, a new U.S. study finds.

People with chronic kidney disease suffer a progressive, permanent loss of kidney function, eventually resulting in the need for dialysis or a kidney transplant. Chronic kidney disease is also believed to increase the risk of cardiovascular illness, according to background information in a news release.

This study of more than 20,000 people (7.6 percent with chronic kidney disease) taking part in a long-term study of heart disease risk factors found that chronic kidney disease patients have a 22 percent higher overall stroke risk than people without kidney disease.

High blood pressure was associated with a higher stroke risk in both chronic kidney disease patients and in people without kidney disease. For each 10-mm Hg increase in systolic blood pressure (the first, higher number in a blood pressure reading), stroke risk increased by 18 percent.

A normal blood pressure reading is around 120/80 mm Hg.

The study also found that low blood pressure increased stroke risk for chronic kidney disease patients. Among those with moderate chronic kidney disease, the stroke rate was more than double for those whose systolic blood pressure was less than 120 mm Hg, compared to those with systolic reading of 120 to 129 mm Hg.

"This effect was most significant in individuals receiving drugs to lower blood pressure," Dr. Daniel E. Weiner, of Tufts-New England Medical Center in Boston, said in a prepared statement.

"The fact that this was an observational study rather than a randomized controlled trail precludes any comment about possible harm related to treating patients to lower blood pressure goals, but it's an area that may benefit from further investigation," Weiner said.

The association between kidney disease, blood pressure and stroke risk is unclear, but the results of this study suggest a number of 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. 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," Weiner said.

The findings are published in the March issue of theAmerican Society of Nephrology.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about chronic kidney disease.

SOURCE: American Society of Nephrology, news release, Feb. 14, 2007

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