Key Point

Obstructive sleep apnea may be linked to an increased risk of death in stroke patients.

Patients with stroke and comorbid obstructive sleep apnea (OSA) may have an increased risk of early mortality, according to Carin Sahlin, BSc, of the Department of Respiratory Medicine at Umeå University Hospital in Sweden, and colleagues. However, central sleep apnea (CSA) was not related to early death among stroke patients in the study, published in the February 11 Archives of Internal Medicine.

Dr. Sahlin and colleagues invited 151 patients admitted to an in-hospital stroke rehabilitation unit from April 1995 to May 1997 to participate in the study. Of these, 13 refused, and six were excluded because of failure in sleep apnea recordings. The remaining 132 patients underwent overnight sleep apnea recordings at a mean of 23 days after stroke onset and were followed up prospectively for a mean of 10 years. The researchers used an apnea-hypopnea index of 15 or greater to define OSA, while a central apnea-hypopnea index of 15 or greater was used to define CSA.

Twenty-three patients had OSA, and 28 had CSA during Cheyne-Stokes respiration. Seventy-nine patients had central and obstructive apnea-hypopnea indexes of less than 15 and served as controls; two patients who had both OSA and CSA were excluded from further analysis. One hundred sixteen patients died during follow-up; this included all patients with OSA, 96.4% of patients with CSA, and 81.0% of controls. The investigators found a 75% increase in the risk of mortality among patients with OSA than in controls. This association was independent of age, sex, BMI, smoking, hypertension, diabetes mellitus, atrial fibrillation, Mini-Mental State Examination score, and Barthel index of activities of daily living. However, there was no difference in mortality rates between patients with CSA and controls.

Possible mechanisms resulting in increased mortality among patients with stroke and sleep apnea “include nocturnal hypoxemia and an increase in the risk of sudden cardiovascular death during sleep,” the researchers stated. “The changes in cerebral blood flow velocity may be an immediate result of changes in blood pressure, and cerebral autoregulation may be insufficient to protect the brain from the rapid [and] potentially harmful arterial pressure changes that occur during obstructive apnea.”

Dr. Sahlin and colleagues suggested that sleep apnea recordings should be performed in patients with stroke and that continuous positive airway pressure should be offered to stroke patients with OSA. Other treatment possibilities include an individually made mandibular advancement appliance for OSA (which thus far has been untested in stroke patients) and avoidance of the supine position.

—John Merriman

Suggested Reading
Sahlin C, Sandberg O, Gustafson Y, et al. Obstructive sleep apnea is a risk factor for death in patients with stroke: a 10-year follow-up. Arch Intern Med. 2008;168(3):297-301.

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