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Obstructive Sleep Apnea May Precede Stroke: Presented at ISC

By Paula Moyer

SAN DIEGO, CA -- February 9, 2004 -- Just as stroke survivors are more likely to have sleep apnea, people with sleep apnea are at greater risk of developing stroke, according to findings presented here February 6^th at the American Stroke Association's 29^th International Stroke Conference.

"We've known that there was a strong relationship between obstructive sleep apnea in stroke survivors, but it was unclear whether the obstructed breathing was a risk factor for stroke or a consequence of it," said H. Klar Yaggi, MD, MPH, professor of pulmonary and critical care medicine, Yale University School of Medicine, and staff, Yale Center for Sleep Medicine, New Haven, Connecticut.

To determine if obstructive sleep apnea was an independent risk factor for development of stroke, Dr. Yaggi and colleagues quantified the relationship between obstructive sleep apnea and transient ischemic attack (TIA), stroke, or death in a prospective cohort study. They assessed 3,365 patients who had been referred to the Yale Center for Sleep Medicine for evaluation of sleep-disordered breathing from October 1997 to December 1999.

Of these patients, 1,052 were diagnosed as having obstructive sleep apnea using overnight polysomnography. The investigators defined obstructive sleep apnea as an apnea-hypopnoea index (AHI) consisting of more than 5 events per hour.

The investigative team assessed subsequent cerebrovascular events and obtained information regarding registrants' death from any cause available in the vital records maintained by the Connecticut Department of Public Health. Analysis consisted of a time to the composite end point of TIA, stroke, or death, and rates of obstructive sleep apnea. Statistical analyses consisted of the Kaplan-Meier log rank test and a multivariable analysis that used the proportional-hazards method.

Among the 1,052 participants, the investigators gathered follow-up data on 845 (80%). The investigators found that 75% of patients with obstructive sleep apnea survived event free for 5 years compared to 88% of those without the sleep disorder (P = .04). Patients with sleep apnea were more than twice as likely to develop TIA or stroke, or to die, compared to their non-affected counterparts (hazard ratio=2.18; P = .04).

As sleep apnea increased, so did the association with an increased risk of TIA, stroke, or death (linear test of trend; P = .04). The multivariate analysis showed that obstructive sleep apnea was an independent predictor of TIA, stroke, or death, even after adjusting for male gender, body mass index, hypertension, and diabetes.


[Study title: Obstructive Sleep Apnea Is a Risk Factor for the Development of Stroke: A Prospective Cohort Study. Abstract P327]

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