Patients with stroke and obstructive sleep apnoea have an increased risk of early death. Sleep apnoea is a disorder of disrupted breathing during sleep. It occurs frequently among patients with stroke, but it is still unknown whether a diagnosis of sleep apnoea is an independent risk factor for mortality. To better understand this relationship, researchers in Sweden examined 151 patients admitted for in-hospital stroke rehabilitation between 1995 and 1997. Among these 132 patients underwent overnight sleep apnoea recordings. A total of 23 patients (about 17 per cent) had obstructive sleep apnoea (in which breathing is blocked by collapsing airway tissues) and 28 patients (about 21 per cent) had central sleep apnoea (in which respiration controlled by the brain is interrupted). Two patients who had both obstructive and central sleep apnoea were excluded. A total of 79 patients served as controls. All the patients underwent overnight sleep apnoea recordings about three weeks after their stroke, and were followed for an average of 10 years. It was found that 116 (88 per cent) patients had died at follow-up, which included all the patients with obstructive sleep apnoea, 96 per cent of those with central sleep apnoea, and 81 per cent of patients without either form of sleep apnoea. The findings showed that the mortality rates of patients with obstructive sleep apnoea were 76 per cent higher than in patients without apnoea. Central sleep apnoea was not associated with increased mortality. This suggests that a drop in nighttime levels of oxygen in the bloodstream and an increased risk of cardiac arrest may account for the increased mortality among stroke patients who have sleep apnoea.
Archives of Internal Medicine,
February 2008