Original article Correlation of Epworth Sleepiness ...

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test and its diagnostic accuracy in assessing excessive daytime ... Background Excessive daytime sleepiness (EDS) is often associated with obstructive sleep ...
Chinese Medical Journal 2013;126 (17)

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Original article Correlation of Epworth Sleepiness Scale with multiple sleep latency test and its diagnostic accuracy in assessing excessive daytime sleepiness in patients with obstructive sleep apnea hypopnea syndrome CAI Si-jie, CHEN Rui, ZHANG Yan-lin, XIONG Kang-ping, LIAN Yi-xin, LI Jie, SHEN Jiu-cheng and LIU Chun-feng Keywords: obstructive sleep apnea hypopnea syndrome; excessive daytime sleepiness; multiple sleep latency test; Epworth Sleepiness Scale; polysomnography Background Excessive daytime sleepiness (EDS) is often associated with obstructive sleep apnea hypopnea syndrome (OSAHS) and contributes to a number of comorbidities in these patients. Therefore, early detection of EDS is critical in disease management. We examined the association between Epworth Sleepiness Scale (ESS) and multiple sleep latency test (MSLT) and diagnostic accuracy of ESS in assessing EDS in OSAHS patients. Methods The ESS, MSLT and overnight polysomnography were administered to 107 Chinese patients to assess EDS and its correlations with polysomnographic parameters. The diagnostic accuracy of ESS in classifying EDS (mean sleep latency (MSL) ≤10 minutes) was evaluated by calculating the area under ROC curve. Results As the severity of OSAHS increased, MSL decreased with increase in ESS score. Conversely, patients with worsening EDS (shorter MSL) were characterized by advanced nocturnal hypoxaemia and sleep disruption compared to those with normal MSL, suggesting EDS is associated with more severe OSAHS. There was a negative correlation between ESS score and MSL and both moderately correlated with some polysomnographic nocturnal hypoxaemic parameters. The area under ROC curve of ESS for identifying EDS was 0.80 (95% CI: 0.71 to 0.88) and ESS score ≥12 provided the best predictive value with a sensitivity of 80% and specificity of 69%. Conclusion The ESS score moderately correlates with MSL and our ROC study supports ESS as a screening strategy for assessing EDS in OSAHS. Chin Med J 2013;126 (17): 3245-3250

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xcessive daytime sleepiness (EDS) is one of the most frequent complaints in patients suffering from obstructive sleep apnea hypopnea syndrome (OSAHS).1-3 Although EDS is not present in every OSAHS patient, it has been reported that most severe OSAHS patients are associated with symptoms of EDS.4,5 EDS is also known to be a common predisposing factor for accidents, reduced productivity, neurocognitive impairment and interpersonal and/or social problems.6-8 There have been reports that EDS related functional impairment, such as performance deficits seen in the simulated driving test and could be reversed by nasal continuous positive airway pressure.9-11 Therefore, the early detection and proper measurement of EDS are beneficial in OSAHS patient management. There are various methods reported to evaluate EDS and the multiple sleep latency test (MSLT) and the Epworth Sleepiness Scale (ESS) has been commonly used.12 The MSLT is an established measure for objective daytime sleepiness assessment.12,13 However, it is time consuming, requiring electroencephalogram (EEG) evaluations and other resources of a sleep laboratory, which limits its use as a screening strategy for early detection of EDS. In contrast, ESS is a simple, self-administered, eight item questionnaire for participants to describe or estimate how they doze off inadvertently when engaged in low level stimulation activities.12

A number of studies have provided conflicting evidence regarding the correlation between the mean sleep latency (MSL) measured on MSLT and the ESS score. 14-17 Therefore, we examined the association between subjective ESS score and the objective MSLT in a sample of Chinese OSAHS patients and evaluated the diagnostic accuracy of ESS in identifying OSAHS patients with abnormal MSLT. METHODS Subjects Chinese patients who presented snoring problem with DOI: 10.3760/cma.j.issn.0366-6999.20130690 Department of Respiratory Medicine (Cai SJ, Chen R, Lian YX and Shen JC), Department of Neurology Medicine (Zhang YL, Xiong KP, Li J and Liu CF), Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, China Department of Respiratory Medicine, First People’s Hospital of Kunshan, Kunshan, Jiangsu 215300, China (Cai SJ) Laboratory of Aging and Nervous Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu 215004, China (Liu CF) Correspondence to: Dr. CHEN Rui, Department of Respiratory Medicine, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, China (Tel: 86-512-67784857. Email: [email protected]) This study was supported by grants from the National Natural Science Foundation of China (NSFC) (No. 81170070, No. 81270147), and from the Scientific Research Foundation of the Chinese Ministry of Health (No. W2012w4).

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clinical suspicion of OSAHS were examined between August 2009 and June 2012 at our institution, 107 of 196 were included in this study. Exclusion criteria were as follows: (1) presence of the following sleep disorders according to International Classification of Sleep Disorders diagnosis:18 central sleep apnea, restless legs syndrome, rapid eye movement (REM) sleep behavioural disorder, periodic limb movement disorder and narcolepsy; (2) history of receiving medical intervention for sleep disorders and (3) other diseases such as cancer, severe physical disability and mental disorders, including those requiring concomitant use of medications that would impact the sleep profiles, quality of life and mental health of the patients. Information regarding the patient’s symptomatic complaints, quality of sleep, medical history and concomitant use of medications was obtained through patient interviews and reviews of medical records. The study was approved by the Second Affiliated Hospital of Soochow University Hospital Ethic Board and all patients were informed and consented prior to the study procedures. Polysomnographic study All of the patients underwent an overnight polysomnographic study of at least 7 hours of recording time during the first night of admission. The polysomnographic study included the following: airflow using oronasal thermistors and nasal pressure transducer, thoracic and abdominal respiratory movements, arterial oxygen saturation by pulse oximetry, snoring and body position, electroencephalogram (C3/ A2, C4/A1, O1/A2, and O2/A1), electrooculogram, chin and leg electromyogram and electrocardiogram. The following polysomnographic variables were obtained: apnea hypopnea index (AHI), oxygen desaturation index (ODI), lowest pulse oxygen saturation (LSpO2), time of oxygen saturation