NEW YORK (Reuters Health) - Sleep apnea, in which breathing briefly ceases or becomes blocked numerous times during the night, is a risk factor for early death in people who have had a stroke, according to a new study.
"Sleep apnea occurs frequently among patients with stroke, but it is still unknown whether a diagnosis of sleep apnea is an independent risk factor for mortality," Dr. Karl A. Franklin, of Umea University Hospital, Sweden, and colleagues write in the Archives of Internal Medicine.
To better understand this relationship, the researchers examined long-term survival among 132 stroke patients admitted for in-hospital stroke rehabilitation between 1995 and 1997.
All of the subjects underwent overnight sleep apnea recordings about three weeks after their stroke, and were followed for an average of 10 years.
The investigators report that 116 (88 percent) of the subjects had died at follow-up, which included all of the patients with obstructive sleep apnea (in which breathing is blocked by collapsing airway tissues), 96 percent of those with central sleep apnea (in which respiration controlled by the brain is interrupted), and 81 percent of patients without either form of sleep apnea.
The mortality rates of patients with obstructive sleep apnea were 76 percent higher than in patients without apnea. Central sleep apnea was not associated with increased mortality.
A drop in nighttime levels or oxygen in the bloodstream and an increased risk of cardiac arrest may account for the increased mortality among stroke patients who have sleep apnea, Franklin's team suggests.
SOURCE: Archives of Internal Medicine, February 11, 2008.
The authors report that 23 patients (17.4 percent) had obstructive sleep apnea and 28 patients (21.2 percent) had central sleep apnea during Cheyne-Stokes respiration. Two patients who had both obstructive and central sleep apnea were excluded. A total of 79 patients served as controls.