Agreement between electronic and paper Epworth Sleepiness Scale responses in obstructive sleep apnoea: secondary analysis of a randomised controlled trial undertaken in a specialised tertiary care clinic.

OBJECTIVES: Originally developed as a paper questionnaire, the electronic Epworth Sleepiness Scale (ESS) is widely used in sleep clinics and sleep population research. Despite potential differences between computer-based and conventional questionnaire delivery, studies have not evaluated the agreement between electronic and paper versions of the ESS. Given the widespread use of the ESS, a bias between results would present considerable data concerns. Thus, the aim of this study was to examine agreement between electronic and paper ESS responses in obstructive sleep apnoea (OSA).

DESIGN: We undertook a secondary analysis of baseline data from a randomised controlled trial (ANZCTR: ACTRN12611000847910).

SETTING: Data were collected in a tertiary sleep research laboratory located in Sydney, Australia.

PARTICIPANTS: Data were analysed from 112 adult patients with OSA.

MEASUREMENTS: Patients were given the English version of the ESS as part of a battery of sleep laboratory questionnaires. They completed electronic and subsequently paper ESS questionnaires on the same day.

RESULTS: We found no significant difference between electronic and paper ESS questionnaires (mean=0.1, SD=2.1, 95% CI -0.3 to 0.5, P=0.57) or heteroscedasticity. There was no evidence of bias along the range of the measure. 95% limits of agreement at 4.3 and -4.1 were comparable with previous data.

CONCLUSIONS: We found no evidence of bias between electronic and paper ESS questionnaires in this sample of patients with OSA, as the two formats displayed sufficient agreement to be clinically comparable. Regardless of severity, patients reported the same level of daytime sleepiness with the same level of accuracy across both measures.

TRIAL REGISTRATION NUMBER: ACTRN12611000847910; Pre-results.