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Severe OSA Tied to Poor Prognoses in Stroke Patients

Patients with acute ischemic stroke had a worse prognosis if they had also experienced severe obstructive sleep apnea, based on data from 125 individuals.

Obstructive sleep apnea (OSA) is on the rise, and is associated with pathophysiological changes, and data from previous studies suggest that severe OSA doubles the risk of stroke and increases risk of stroke recurrence, according to Juan Xu, PhD, of Soochow University, Suzhou, China, and colleagues.

“There is a high comorbidity between stroke and OSA,” and effective sleep is important to cerebral function recovery, the researchers wrote. Early prediction of stroke prognosis may inform treatment in stroke patients, but the value of OSA as a predictor of functional prognosis has not been explored, they said.

In a study published in Sleep Medicine, the researchers analyzed data from 125 adults with mild to moderate ischemic stroke and OSA. The participants underwent polysomnography within a week of stroke onset between January 2015 and June 2020 and were grouped by severity according to apnea-hypopnea index of either less than 30/h (not severe) or 30/h or higher (severe). The mean age of the patients was 58 years, and 87% were men. Approximately one third (33.3%) of the participants met the criteria for severe OSA.

The researchers assessed the impact of OSA on functional prognosis in the acute phase of stroke, and reviewed quantitative electroencephalography (EEG) markers in stroke patients during sleep.

Overall, individuals with severe OSA were significantly more likely than those with less severe OSA to have comorbid hypertension (85.4% vs 56%, P = .002) and a higher body mass index (28 vs 24, P < .001). Other factors including blood pressure, smoking history, alcohol use, and comorbid diabetes were similar between the groups.

Quantitative EEG among patients with severe OSA showed lower relative power of high-frequency bands (alpha, beta, and sigma). The EEG also showed higher delta/alpha power ratio (DAR) and slowing ratio (TSR), and higher delta relative power (delta RP) in severe OSA (P < .05 for all).

In addition, severe OSA was associated with more than triple the risk (3.6-fold increase) of poor prognosis, defined as a Modified Rankin Scale score of 3 or higher (24.4% for severe OSA vs 8.3% for nonsevere OSA, P = .03).

“Our study confirmed that severe OSA is an independent risk factor for poor functional prognosis in the acute phase of ischemic stroke,” the researchers wrote in their discussion. “Integrating the alteration of quantitative EEG parameters may improve the accuracy of early predictions of functional prognosis in patients with stroke,” they noted.

The findings were limited by several factors including the retrospective design and the lack of a sizable non-OSA control group, the researchers noted. Other limitations included the use of an AHI of 30/h or higher to define severity and the use of data from medical histories, with the potential for information bias, and the use of only 30-second continuous polysomnography segments, they said.

However, the results suggest that increased delta RP and TSR, and decreased alpha, beta, and sigma RP, may be independent predictors of a poor functional prognosis in stroke patients with OSA, and that the prognosis could be improved by treating the OSA, they concluded.

The study was supported by the Natural Science Foundation of China and the Discipline Construction Program of the Second Affiliated Hospital of Soochow University. The researchers reported no financial conflicts.

Sleep Med. December 5, 2022. Full Text.

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