Obstructive Sleep Apnea Caused Five-Fold Increase in Heart Disease

The first long-term, clinic-based epidemiologic study of the development of cardiovascular disease in middle-aged men either with or without obstructive sleep apnea (OSA) showed that the sleep problem caused almost a 5-fold increase in heart disease which was independent of age, weight, blood pressure, and current smoking status. The research was published in the second issue for July 2002 of the American Thoracic Society's peer-reviewed journal.

Writing in the American Journal of Respiratory and Critical Care Medicine, Yüksel Peker, M.D., Ph.D., of the Department of Pulmonary Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden, along with four associates, found that at least one cardiovascular problem occurred in 22 of 60 men, ages 30 to 69, with OSA, compared with 8 out of 122 without OSA. All subjects were free of hypertension or other heart disease symptoms, pulmonary disease, diabetes, psychiatric disorder, alcohol dependency, or malignancy at baseline in 1991. They were studied over a seven-year period.

In sleep apnea, a person repeatedly stops breathing during sleep long enough to decrease the amount of oxygen in the blood and brain and to increase the amount of carbon dioxide. OSA affects 24 percent of the middle-aged men and 9 percent of the women in the U.S.

The 182 men underwent an overnight sleep study in the sleep lab, lasting about seven hours. Their test included a continuous recording of transcutaneous arterial oxygen saturation.

According to the investigators, the most significant predictor of the development of cardiovascular disease was the presence of OSA at baseline. Patients who had excessive daytime sleepiness were offered treatment with either continuous positive airway pressure, surgery, or an oral appliance.

In the OSA group, cardiovascular disease incidence was observed in 21 of 37 incompletely treated cases, but it occurred in only 1 in 15 of the effectively treated patients.

"When OSA was incompletely treated, the independent risk for cardiovascular disease increased up to 11-fold, whereas effective treatment of OSA significantly reduced the excess risk," said Dr. Peker.

There were five deaths in the original study group of otherwise healthy middle-aged men at the start of the study. Two deaths were attributed to cardiovascular disease and occurred in the incompletely treated group. One patient in the effectively treated OSA group died of cancer. The other two deaths in the non-OSA group were due to cancer and a central neurologic disorder, respectively.

At baseline, the researchers said that OSA was found in almost one-third of the cohort. The patients had been referred to the sleep laboratory because of snoring or witnessed apneas.

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Source: American Thoracic Society