Sleep apnoea may cause heart disease in kidney transplant patients

Sleep apnoea is common in individuals who receive a kidney transplant and is associated with increased risk of high blood pressure, heart disease or stroke, according to a study appearing in the Clinical Journal of the American Society Nephrology (CJASN). Researchers found that kidney transplant patients are just as likely to have this sleep disorder as dialysed kidney disease patients who are on the transplant waiting list. Therefore, both types of patients who have sleep apnoea should be considered at high risk for developing serious heart-related complications.

Cardiovascular disease is the most common cause of death in individuals who receive kidney transplants, and doctors monitor transplant recipients for high blood pressure, or hypertension, and other signs of heart trouble. Obstructive sleep apnoea occurs when an individual stops breathing momentarily during sleep due to obstruction of the airway and has been linked to hypertension. Miklos Zsolt Molnar, MD, PhD (Semmelweis University, Budapest, Hungary), and his colleagues studied the prevalence of sleep apnoea in kidney transplant patients and the effects the condition had on their cardiovascular risk.

The study included 100 transplant recipients. The researchers found that moderate-to-severe sleep apnoea occurred in one of every four individuals. This rate was similar to that seen in a group of dialysed kidney disease patients who were waiting for a transplant. In addition, kidney transplant patients with sleep apnoea were more than twice as likely to be taking three or more anti-hypertensive drugs as patients without the sleep disorder but still displayed higher blood pressure than patients who slept normally. As seen in the general population, being obese increased patients’ risk of developing sleep apnoea. When risk scores were calculated to predict patients’ risk of developing heart disease or experiencing a stroke, kidney disease patients who had sleep apnoea had twice the risk as patients without apnoea.

"We propose that sleep apnoea is a new risk factor for hypertension and cardiovascular events in kidney transplanted patients," said Dr Molnar. "Physicians should screen transplant patients for obstructive sleep apnoea and offer appropriate treatment," the authors explain.

(Source: American Society of Nephrology: Clinical Journal of the American Society Nephrology: November 2009)