Obstructive sleep apnea-hypopnea and incident stroke: the sleep heart health study

Abstract

Rationale: Although obstructive sleep apnea is associated with physiological perturbations that increase risk of hypertension and are proatherogenic, it is uncertain whether sleep apnea is associated with increased stroke risk in the general population.

Objectives: To quantify the incidence of ischemic stroke with sleep apnea in a community-based sample of men and women across a wide range of sleep apnea.

Methods: Baseline polysomnography was performed between 1995 and 1998 in a longitudinal cohort study. The primary exposure was the obstructive apnea-hypopnea index (OAHI) and outcome was incident ischemic stroke.

Measurements and main results: A total of 5,422 participants without a history of stroke at the baseline examination and untreated for sleep apnea were followed for a median of 8.7 years. One hundred ninety-three ischemic strokes were observed. In covariate-adjusted Cox proportional hazard models, a significant positive association between ischemic stroke and OAHI was observed in men (P value for linear trend: P = 0.016). Men in the highest OAHI quartile (>19) had an adjusted hazard ratio of 2.86 (95% confidence interval, 1.1-7.4). In the mild to moderate range (OAHI, 5-25), each one-unit increase in OAHI in men was estimated to increase stroke risk by 6% (95% confidence interval, 2-10%). In women, stroke was not significantly associated with OAHI quartiles, but increased risk was observed at an OAHI greater than 25.

Conclusions: The strong adjusted association between ischemic stroke and OAHI in community-dwelling men with mild to moderate sleep apnea suggests that this is an appropriate target for future stroke prevention trials.

Figure 1.

Study schema showing derivation of the analytical sample. CPAP = continuous positive airway pressure.

Figure 2.

Adjusted Kaplan-Meier stroke-free survival estimates as a function of obstructive apnea–hypopnea index (OAHI) quartile. Values are modeled in this graph for white current smoker (A) men and (B) women with no use of antihypertensive medications with mean values of other covariates. The first (OAHI <4.5), second (4.05–9.5), third (9.5–19.1), and fourth quartiles (>19.1) of the OAHI are shown by the various solid and dashed lines indicating the quartiles (see key at bottom of figure).