Purpose

Obstructive sleep apnea (OSA) is underdiagnosed, partially from variable clinical presentations. Emphasis is often placed on Epworth Sleepiness Scale (ESS), a subjective measure of sleepiness, but variable in OSA. We hypothesized that daytime complaints measured with Language of Sleepiness Questionnaire (LOS) in OSA are not being captured by ESS.

Methods

Adults referred to a tertiary sleep clinic undergoing sleep studies completed ESS and LOS questionnaires (20 items with various patient-reported descriptors). LOS was examined in patients who had or did not have OSA without sleepiness based on ESS < 10. Cluster analysis was performed to assess whether or not groups of individuals differed based on classification with or without OSA and with or without ESS-based sleepiness.

Results

Approximately half the study population (n = 185 completed) had OSA. ESS score (mean ± SD) was 9.0 ± 5.4. There was no significant difference in ESS between patients with and without OSA (9.0 ± 5.1 vs 9.1 ± 5.7, p = 0.969). In patients with OSA, females, older patients and white patients were significantly less likely to have an ESS ≥ 10 when compared to patients with an ESS < 10. In patients with an ESS < 10, there were no significant differences in descriptors of sleepiness between patients with and without OSA with the most common descriptors selected being "I lack energy," "I wake up sleepy," "I keep waking up," and "I don't sleep enough."

Conclusions

The ESS failed to discriminate patients with OSA from those without OSA. Despite an ESS < 10, both daytime and sleep complaints using the LOS questionnaire were present in patients with OSA. Asymptomatic OSA may be less common than previously reported.