Observation and interview-based diurnal sleepiness inventory for measurement of sleepiness in patients referred for narcolepsy or idiopathic hypersomnia

STUDY OBJECTIVES:First, to determine whether the three-item ODSI (Observation and interview based Diurnal Sleepiness Inventory) measures the degree of excessive daytime sleepiness (EDS) in patients with suspected narcolepsy or idiopathic hypersomnia (IH). Second, to assess the correlation between the ODSI and the Epworth Sleepiness Scale (ESS) as well as objective polysomnographic measurements. Third, to test the accuracy of the ODSI to detect narcolepsy or idiopathic hypersomnia (narcolepsy/IH) compared to the ESS.
METHODS:A total of 181 patients complaining of EDS filled in the ESS, the ODSI and underwent measurements including actigraphy, full-night polysomnography, Multiple Sleep Latency Test (MSLT), and 24h bed-rest sleep recording.
RESULTS:Narcolepsy or idiopathic hypersomnia was diagnosed in 76 patients. The ODSI found EDS in 92.3% of all patients and in 98.7% of those diagnosed with narcolepsy/IH. In the whole population, the ODSI was significantly positively correlated with the ESS (R=0.547, 95% CI [0.436, 0.642], p<0.001) and, weakly, with 24-total sleep time (TST) on bed-rest recording (R=0.208, 95% CI [0.056, 0.350], p=0.047) but not with the MSLT. The ODSI offered a higher negative (92.9%) and positive (44.9%) predictive values to detect narcolepsy/IH than did the ESS (66.7% and 43.3% respectively). The ODSI’s 3rd item score (daily sleepiness duration), was significantly higher among IH patients with than without increased 24-TST (>660min) (p=0.023).
CONCLUSIONS:The ODSI is a brief, simple first line questionnaire which explores both intensity and duration of daytime sleepiness and offers a high sensitivity to detect narcolepsy and IH.