Abstract
Objective:
To test the hypothesis that risk status for obstructive sleep apnea (OSA) is associated with time of onset in intracerebral hemorrhage.
Background:
OSA can affect 30-70% of patients with ischemic strokes, intracerebral hemorrhage and transient ischemic attacks. In normal sleep, blood pressure and heart rate decrease due to increased parasympathetic activity. In OSA, increased sympathetic activity during sleep can lead to a absence of this blood pressure fall. This non-dipping nocturnal blood pressure pattern has been associated with a shift in the timing of sudden cardiac death, from 7am-noon in those without OSA to 12am-6am in those with OSA. Whether this diurnal shift exists in intracerebral hemorrhage cases at high risk for OSA has not been studied.
Method:
A nested case control study within the interviewed case cohort from the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study was performed. OSA risk status was categorized as “high-risk” based on a positive score in 2 out of 3 categories on the Berlin questionnaire, which ascertains snoring, daytime fatigue, body mass index and hypertension. Timing of intracerebral hemorrhage was categorized as “Nocturnal” based on a known time of stroke onset from 22:00pm to 06:00am and “Awake” based on a known time of stroke onset from 06:01am to 21:59pm.
Results:
Time of stroke onset was known in 434 subjects. The Berlin questionnaire categorized 54.2% of cases as high-risk for OSA. In comparison with low-risk subjects, high-risk cases tended to be younger (59.1±13.7 vs. 61.8±15.7, p=0.05), male (48% vs 58%, p=0.03), have coronary disease (6% vs 11%, p=0.09), have diabetes (27% vs 18%, p=0.02), and have dyslipidemia (43% vs 30%, p=0.006). There were no ethnic differences in the prevalence of high risk for OSA (P=0.60). Nocturnal strokes were seen in 17% of high- and low-risk OSA cases. There was no statistically significant difference in OSA status and timing of stroke (p=0.98).
Conclusions:
OSA risk status was not associated with timing of hemorrhagic stroke. This finding suggests that a non-dipping nocturnal blood pressure pattern is not seen in intracerebral hemorrhage cases at high-risk for OSA.