Modification of the Epworth Sleepiness Scale in Central ChinaReport as inadecuate

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Quality of Life Research

, Volume 20, Issue 10, pp 1721–1726

First Online: 12 April 2011Accepted: 18 March 2011


PurposeThe well-known excessive daytime sleepiness EDS assessment, Epworth Sleepiness Scale ESS, is not consistently qualified for patients with diverse living habits. This study is aimed to build a modified ESS mESS and then to verify its feasibility in the assessment of EDS for patients with suspected sleep-disordered breathing SDB in central China.

MethodsA Ten-item Sleepiness Questionnaire 10-ISQ was built by adding two backup items to the original ESS. Then the 10-ISQ was administered to 122 patients in central China with suspected SDB among them, 119 cases met the minimal diagnostic criteria for obstructive sleep apnea by sleep study, e.g., apnea and hypopnea index AHI ≥ 5 h and 117 healthy central Chinese volunteers without SDB. Multivariate exploratory techniques were used for item validation. The unreliable item in the original ESS was replaced by the eligible backup item, thus a modified ESS mESS was built, and then verified.

ResultsItem 8 proved to be the only unreliable item in central Chinese patients, with the least factor loading on the main factor and the lowest item-total correlation both in the 10-ISQ and in the original ESS, deletion of it would increase the Cronbach’s alpha from 0.86 to 0.87 in the 10-ISQ; from 0.83 to 0.85 in the original ESS. The mESS was subsequently built by replacing item 8 in the original ESS with item 10 in the 10-ISQ. Verification with patients’ responses revealed that the mESS was a single-factor questionnaire with good internal consistency Cronbach’s alpha = 0.86. The sum score of the mESS not only correlated with AHI P < 0.01 but was also able to discriminate the severity of obstructive apnea P < 0.01. Nasal CPAP treatment for severe OSA reduced the score significantly P < 0.001. The performance of the mESS was poor in evaluating normal subjects.

ConclusionThe mESS improves the validity of ESS for our patients. Therefore, it is justified to use it instead of the original one in assessment of EDS for patients with SDB in central China.

KeywordsEpworth Sleepiness Scale Excessive daytime sleepiness Sleep-disordered breathing AbbreviationsAHIApnea and hypopnea index

CPAPContinuous positive airway pressure

EDSExcessive daytime sleepiness

ESSEpworth Sleepiness Scale

mESSModified Epworth Sleepiness Scale

OSAObstructive sleep apnea

SpO2 < 90Percentage of sleep time with oxygen saturation below 90%

SDBSleep-disordered breathing

10-ISQTen-item Sleepiness Questionnaire

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Author: Jin Nong Zhang - Bo Peng - Ting Ting Zhao - Min Xiang - Wei Fu - Yi Peng


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