Obstructive Sleep Apnea as a Risk Factor for Stroke and Death

Abstract

The obstructive sleep apnea syndrome significantly increases the risk of stroke or death from any cause, and the increase is independent of other risk factors, including hypertension.

The Determining Risk of Vascular Events by Apnea Monitoring (DREAM) study: design, rationale, and methods

“…Obstructive sleep apnea (OSA), a common form of sleepdisordered breathing, has a high and rising prevalence (17%) in the general adult population, attributable in part to enhanced awareness and the emerging epidemic of obesity [2][3][4]. OSA has also been independently linked to important health outcomes, including hypertension [5], fatal and nonfatal cardiovascular events [6,7], stroke [8], and metabolic dysfunction [9].…”

“…The enumeration of these events-per-hour of sleep yields the apnea-hypopnea index (AHI). Clinically, this metric defines sleep apnea severity, but it has also been shown to relate to cardiovascular disease, including hypertension [5], coronary heart disease [14], and stroke [8]. Standard polysomnography also records a rich array of other physiologic measurements.…”

“…Based on an accrual interval of 4 years, a mean follow-up interval of 5 years, and a median time to event of 3 years (estimated from previous work) a sample size of 2200 allows for a minimal detectable hazard ratio of 1.15 with 80% power and α=0.05 [8]. The study is therefore powered adequately to detect an association between individual sleep variables and the development of acute coronary syndrome (which represents the most conservative estimate of the three primary endpoints).…”

Association of sleep apnea with clinically silent microvascular brain tissue changes in acute cerebral ischemia

“…Stroke clinicians have recognized sleep apnea as an independent risk factor for clinically apparent ischemic strokes [22][23][24]. It is unclear, however, whether sleep apnea contributes to the development of chronic microvascular brain tissue changes.…”

“…The collection of both TIA and acute stroke patients may have added another bias to our results. However, larger observational studies suggest that sleep apnea precedes acute stroke events (establishing it as a risk factor as opposed to a clinical manifestation of acute brain damage) and only a minority of patients experience relevant improvement of their sleep pattern over time [22,23,35]. Second, patients with gait and urinary incontinence were not excluded diminishing the validity whether the radiological classified chronic microvascular brain tissue changes were ultimately "silent".…”