Longer duration electroencephalogram arousals have a better relationship with impaired vigilance and health status in obstructive sleep apnoea

Purpose: Obstructive sleep apnoea (OSA) is a prevalent sleep disorder with significant health consequences. Sleep fragmentation is a feature of OSA and is often determined by the arousal index (ArI), a metric based on the electroencephalograph (EEG). The ArI has a weak correlation with neurocognitive outcomes in OSA patients. In this study, we examine whether changing from the current minimum EEG arousal duration of 3 s improves the association between sleep fragmentation and neurocognitive outcomes. Methods: In a retrospective study, we selected OSA patients without any other comorbidities that are associated with neurocognitive impairment. The OSA patients were clustered into two groups based on their psychomotor vigilance task (PVT) performance to represent impaired and unimpaired neurocognition. Results: While no differences were found in demographics or usual sleep study statistics, the impaired group had a greater number of EEG arousals greater than 5 s (P = 0.034), 7 s (P = 0.041), and 15 s (P = 0.036) in duration. There were no differences in the number of EEG arousals associated with sleep-disordered breathing events. These differences also corresponded with quality of life outcomes between the two groups. An ArI with a duration of 5 s or greater had the best combination of sensitivity (70.0%) and specificity (66.7%) compared with the usual 3 s duration (sensitivity and specificity of 70.0% and 53.3%, respectively). Conclusion: A re-examination of the EEG arousal scoring rules, and their duration, may help with allocation of health resources to OSA patients most in need.