SAN DIEGO—Stroke incidence rates in peritoneal dialysis (PD) patients may be lower than in hemodialysis (HD) patients, according to the largest published study of its kind.

The difference may be related to case mix, volume status, disease management, and routine exposure to anticoagulation, researchers stated.

“We looked at a large population at three centers in London,” said lead investigator Albert Power, MD, of the Imperial College Kidney and Transplant Centre, Hammersmith Hospital, London, U.K. “It may be related to less blood pressure flux with treatment. The second reason in terms of hemorrhagic strokes would be there is no routine exposure to anticoagulants three times a week as you get with hemodialysis.”

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The retrospective study included 1,511 PD patients with a mean age of 54.7 years. Of these, 7% had pre-existing cerebrovascular disease. The investigators defined stroke as an acute neurologic event that is greater than 24 hours duration and confirmed on neuroimaging. The researchers excluded cases of subdural hematoma.

Over 3,672 patient-years of follow-up, 39 strokes occurred, for an overall incidence of 10.6 strokes per 1,000 patient-years. By comparison, during this same time period, the incidence of stroke in the U.K. general population varied from 1.0 to 1.5 per 1,000 patient-years. Eighty-two percent of the strokes were ischemic and 18% were hemorrhagic. The median PD vintage at the time of stroke was 2.0 years, according to the researchers.

The stroke rates found with PD patients in the U.K. are significantly lower than strokes rates for HD patients in the United States (26 per 1,000 patient-years) for a number of reasons. “It may well be the effect of residual renal function exerts a modulatory effect on systemic inflammation that is linked to accelerated atherosclerosis and certainly an ischemic stroke is believed to be an atherosclerotic event,” Dr. Power said.

Stephen Sozio, MD, Assistant Professor, Division of Nephrology, Johns Hopkins University, Baltimore, said stroke is becoming a well-recognized complication of both chronic kidney disease and end stage renal disease (ESRD) that results in a lower quality of life, increased disability, and increased mortality for patients. “This study confirms the five- to 10-fold higher risk of stroke in those with ESRD seen in other studies, and adds additional insight into the risk for those on peritoneal dialysis,” Dr. Sozio said. “Even after this study, we still do not know whether peritoneal dialysis or hemodialysis poses the lowest risk of stroke. These are important issues for our patients, and more studies such as this one need to be conducted to reduce stroke and its complications in those with ESRD.”

Dr. Sozio noted that a direct comparison of stroke risk between PD patients in the U.K. and HD patients in the U.S. is difficult to interpret.