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Minimum important difference of the Epworth Sleepiness Scale in obstructive sleep apnoea: estimation from three randomised controlled trials


Crook, Sarah; Sievi, Noriane A; Bloch, Konrad E; Stradling, John R; Frei, Anja; Puhan, Milo A; Kohler, Malcolm (2019). Minimum important difference of the Epworth Sleepiness Scale in obstructive sleep apnoea: estimation from three randomised controlled trials. Thorax, 74(4):390-396.

Abstract

BACKGROUND The Epworth Sleepiness Scale (ESS) is a widely used tool for assessing sleepiness in patients with obstructive sleep apnoea (OSA). We aimed to estimate the minimal important difference (MID) in patients with OSA. METHODS We used individual data from three randomised controlled trials (RCTs) in patients with OSA where the preintervention to postintervention change in ESS was used as a primary outcome. We used anchor-based linear regression and responder analysis approaches to estimate the MID. For anchors, we used the change in domains of the Functional Outcomes of Sleep Questionnaire and 36-Item Short Form Health Survey. We also used the distribution-based approaches Cohen's effect size, SE of measurement and empirical rule effect size to support the anchor-based estimates. The final MID was determined by triangulating all estimates to a single MID. FINDINGS A total of 639 patients with OSA were included in our analyses across the three RCTs with a median (IQR) baseline ESS score of 10 (6-13). The median (IQR) ESS change score overall was -2 (-5 to 1). The anchor-based estimates of the MID were between -1.74 and -4.21 points and estimates from the responder analysis were between -1 and -3 points. Distribution-based estimates were smaller, ranging from -1.46 to -2.36. INTERPRETATION We propose an MID for the ESS of 2 points in patients with OSA with a disease severity from mild to severe. This estimate provides the means to plan trials and interpret the clinical relevance of changes in ESS. TRIAL REGISTRATION NUMBER Provent, NCT01332175; autoCPAP trial, NCT00280800; MOSAIC,ISRCTN (3416388).

Abstract

BACKGROUND The Epworth Sleepiness Scale (ESS) is a widely used tool for assessing sleepiness in patients with obstructive sleep apnoea (OSA). We aimed to estimate the minimal important difference (MID) in patients with OSA. METHODS We used individual data from three randomised controlled trials (RCTs) in patients with OSA where the preintervention to postintervention change in ESS was used as a primary outcome. We used anchor-based linear regression and responder analysis approaches to estimate the MID. For anchors, we used the change in domains of the Functional Outcomes of Sleep Questionnaire and 36-Item Short Form Health Survey. We also used the distribution-based approaches Cohen's effect size, SE of measurement and empirical rule effect size to support the anchor-based estimates. The final MID was determined by triangulating all estimates to a single MID. FINDINGS A total of 639 patients with OSA were included in our analyses across the three RCTs with a median (IQR) baseline ESS score of 10 (6-13). The median (IQR) ESS change score overall was -2 (-5 to 1). The anchor-based estimates of the MID were between -1.74 and -4.21 points and estimates from the responder analysis were between -1 and -3 points. Distribution-based estimates were smaller, ranging from -1.46 to -2.36. INTERPRETATION We propose an MID for the ESS of 2 points in patients with OSA with a disease severity from mild to severe. This estimate provides the means to plan trials and interpret the clinical relevance of changes in ESS. TRIAL REGISTRATION NUMBER Provent, NCT01332175; autoCPAP trial, NCT00280800; MOSAIC,ISRCTN (3416388).

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Epidemiology, Biostatistics and Prevention Institute (EBPI)
04 Faculty of Medicine > University Hospital Zurich > Clinic for Pneumology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:April 2019
Deposited On:04 Jan 2019 08:23
Last Modified:16 Mar 2019 02:03
Publisher:BMJ Publishing Group
ISSN:0040-6376
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1136/thoraxjnl-2018-211959
Related URLs:https://thorax.bmj.com/content/early/2018/08/11/thoraxjnl-2018-211959.long
PubMed ID:30100576

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