The increased risk of stroke for patients with OSA is well documented. The reason for this is not well understood. OSA reduces blood oxygen, elevates blood pressure, fragments sleep and causes sleep loss. All of which could potentially contribute to the increased risk of stroke for patients with OSA.
Stone et al. recently conducted an analysis on 2872 community dwelling men with a mean age of 76 who were enrolled in the MrOS sleep study (https://sleepdata.org/datasets/mros). They looked at the sleep study results (from home sleep studies) including obstructive apnoea hypopnoea index, the apnoea hypopnoea index (AHI – this is a parameter reported on TSGQ sleep study reports), central apnoea index, and nocturnal hypoxemia (also reported on TSGQ sleep reports). A physician reviewed the patients’ medical records to obtain the incident of stroke after an average follow up of 7.3 years. It was these two sets of data that were analysed to assess the link between OSA and the incidence of stroke.
156 of the 2872 men (5.74%) had a stroke during follow-up. The men that spent more than 10% of the night with a SpO2 lower than 90% had a 1.8 fold increased risk of stroke (either incident stroke or incident fatal stroke). The analysis initially adjusted for age, clinic site, race, body mass index and smoking status. The results remained the same with further adjustment for potential covariates and excluding men with a history of stroke. They did not find a clear link between other factors noted on the sleep study reports (i.e. AHI) and the likelihood of stroke.
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Stone et al. concluded that older men (in the community) with severe nocturnal hypoxemia (10% <90% SpO2) are at significantly increased risk of stroke.
