Agreement between Epworth Sleepiness Scale and objective sleep parameters in patients with excessive daytime sleepiness

Obstructive sleep apnea (OSA) is a disease with a broad social impact. Excessive daytime sleepiness raises suspicion of OSA and together with polysomnography (PSG) is the basis for diagnosis. The Epworth Sleepiness Scale (ESS) is used for objective assessment of daytime sleepiness. Many authors underline a high predictive value of this scale in selecting patients at risk of OSA. Moreover, there is a high agreement between the ESS and PSG. However, some authors oppose the use of this scale. We wanted to verify this issue based on our own data. We enrolled 120 patients who were referred to the Polysomnographic Laboratory, Department of Otolaryngology, Medical University of Warsaw with a suspicion of obstructive sleep apnea. All patients filled out the Epworth Sleepiness Scale. Overnight PSG was performed with 14-channel recordings (Grassm USA), including EEG, EMG, and recordings of the movements of the chest and abdomen. Airflow through the airways was recorded with a nasal-oral temperature probe. PSG was assessed automatically and manually; sleep stages were coded manually for each 30-second interval by a technician. Severity of OSA was assessed based on AHI. There were 96 patients with confirmed OSA and a control group of 24 patients with exclusion of OSA but with different disorders causing excessive daytime sleepiness. The average ESS scores were not significantly different between the subgroups, between genders, and in patients with different severity of OSA. ESS scores did not correlate significantly with any of the tested PSG parameters. In conclusion, the ESS should be used as an additional and only ancillary tool in assessing patients with suspected OSA.