Introduction: There is no established reference standard for subjective measures of sleepiness in older adults.
Methods: This study compares the Observation and Interview-based Diurnal Sleepiness Inventory (ODSI) with two existing instruments for measurement of sleepiness and daily functioning, the Epworth Sleepiness Scale (ESS) and Functional Outcomes of Sleep Questionnaire (FOSQ).
Results: A total of 125 study participants were included in this study and were administered the ODSI, ESS and FOSQ; subjects had a mean age of 70.9 ± 5.27 years, mean Apnea–Hypopnea Index of 31.9 ± 27.9 events/hour and normal cognitive functioning (Mini-Mental State Examination score > 24). The ODSI showed a significant association with the ESS (Spearman’s ρ: 0.67, P < 0.001) and with the FOSQ (Spearman’s ρ: –0.52, P < 0.001). The ODSI 1 item (assessing sleepiness in active situations) was borderline significantly correlated with the ESS (β = 0.14; 95% confidence interval [CI], –0.01 to 0.29; P = 0.069). ODSI 2 item (sleepiness in passive situations) was correlated with the ESS (β = 1.65; 95% CI, 1.32 to 1.98; P < 0.001). Both ODSI 1 (β = –0.15; 95% CI, –0.24 to –0.07; P < 0.001) and ODSI 2 (β = –0.35; 95% CI, –0.55 to 0.16; P < 0.001) were significantly correlated with the FOSQ.
Conclusion: The ODSI is a suitable measure of sleepiness and is appropriate for usage in clinical care in older adults.
Keywords: excessive daytime sleepiness, functional status, sleep disorders, questionnaires