Sleepiness and attention in sleep-clinic patients and their associations with apnea severity and treatment

STUDY OBJECTIVES: Excessive daytime sleepiness (EDS) is common in patients with sleep disorders, particularly obstructive sleep apnea (OSA). The Epworth Sleepiness Scale (ESS) and the Psychomotor Vigilance Test (PVT) are often used to measure sleepiness and attention/vigilance, respectively. However, whether these measures are correlated and their relationship to OSA severity/treatment remains understudied. This study examined these associations in a sleep center population. METHODS: We performed a prospective study of 165 participants (119 [72.1%] with diagnosed OSA) presenting to a sleep disorders clinic and completing ESS and PVT. Associations among ESS, PVT, OSA severity, and positive airway pressure (PAP) usage and efficacy were examined using Pearson's correlations, unadjusted and controlling for age, sex, and body mass index. RESULTS: Results showed no significant correlations between ESS and PVT measures of attention/vigilance. While higher ESS scores correlated with more severe apnea-hypopnea indices in patients with OSA, no association was found with OSA severity and PVT measures. Among participants using PAP, greater hours/night of usage was associated with lower ESS scores, but not with better PVT performance. CONCLUSIONS: We found no association between sleepiness on the ESS and attention/vigilance on PVT among a sleep center population. ESS scores tracked more closely to OSA severity/treatment than PVT measures. The findings suggest that the sleepiness measured by the ESS and measures of sustained attention under monotonous conditions from the PVT capture distinct symptoms. While the ESS is commonly used, further research is needed to determine if the PVT should also be incorporated into clinical practice.