More ‘skewed’
The results for sleep duration were relatively “skewed,” said Dr. Duss. More patients reported longer sleep duration (more than 9 hours) at 1 month than at month 3, and more reported shorter sleep duration (4.0 hours or less) at month 3 than at month 1.
The researchers built a sleep burden index for the combined impact of the various sleep-wake disturbances.
They used this index as a predictor of subsequent cardiocerebrovascular events within 3 months after an event. They used a composite outcome that included recurrent stroke or TIA, MI, heart failure, and urgent revascularization, as well as new cardiocerebrovascular events, from 3 to 24 months.
The analysis showed that the mean sleep burden index was higher for stroke patients with a recurrent event, compared with stroke or TIA patients without a recurrent event (P = .0002).
A multiple logistical regression model with the presence or absence of a recurrent event as an outcome showed that the sleep burden index is a significant predictor of recurrent events (odds ratio, 2.10; P = .001). This was true even after controlling for age, gender, and baseline stroke severity.
The baseline apnea/hypopnea index and sleep duration were also significant predictors of new events. Importantly, though, the sleep burden index remained a significant predictor of recurrent events even after excluding the apnea/hypopnea index component, said Dr. Duss. “So the predictive power of the sleep burden index is not only driven by the apnea-hypopnea index at the beginning of a stroke.”
Sleep-wake disturbances “should be more carefully assessed and considered in comprehensive treatment approaches,” not only in stroke patients, but in neurologic patients in general, said Dr. Duss
She noted that these are preliminary observations from an ongoing study. The results need to be confirmed and should be when the study is finalized, she said.
Researchers are also analyzing MRI data to assess whether certain brain lesions are associated with sleep disturbances.
Jesse Dawson, MD, professor of stroke medicine at the University of Glasgow, said the clinical scoring system the study included “will be a big help in design and conduct of clinical trials.”
Although he and other stroke experts are aware of the high prevalence of sleep disorders after stroke, “we don’t routinely look for them as we’re uncertain whether intervention is of benefit,” said Dr. Dawson.
This new study “suggests there is an association with adverse outcome,” he said.
The research was supported by grants from the Swiss National Science Foundation and the Swiss Heart Foundation. Dr. Duss and Dr. Dawson disclosed no relevant financial relationships.
A version of this article originally appeared on Medscape.com.