Psychometric evaluation of the Epworth Sleepiness Scale in an obstetric population

Background: The Epworth Sleepiness Scale (ESS) was initially developed to measure daytime sleep propensity in patients affected by a variety of sleep disorders. Obstetrical research has measured sleepiness in pregnant women with the ESS, although psychometric analyses and dimensionality evaluations have never been conducted with this population. Objective: The objective was to perform a psychometric evaluation of the ESS in an obstetric population. The design was a secondary data analysis of the subjects enrolled in the Prenatal Exposures and Preeclampsia Prevention III (PEPP) study. The setting for the subjects who received prenatal care was at Magee-Women's Hospital UPMC in Pittsburgh, Pennsylvania and included 337 pregnant women in their first trimester that completed the ESS. Methods: Principal components analysis and confirmatory factor analysis were performed using SPSS and M-Plus. Additionally, reliability was assessed and construct validity was measured using the Life Orientation Test (LOT). Lastly, a relationship between daytime sleepiness and snoring was investigated using item 5e from the Pittsburgh Sleep Quality Index (PSQI). Results: PCA with varimax rotation yielded two factors that explained approximately 50% of the variance and CFA results verified this two-factor solution. An overall Cronbach's alpha (0.751) revealed moderate reliability (Factor 1 alpha = .754; Factor 2 alpha = .524). Both convergent and discriminant validity were established. Conclusion: The ESS is appropriate for use in an obstetric population to measure daytime sleepiness. Future work should include additional evaluations of the ESS in a diverse group of pregnant women. (C) 2012 Elsevier B. V. All rights reserved.