- Email: [email protected]
The Epworth Sleepiness Scale
CHEST
Original Research SLEEP DISORDERS
The Epworth Sleepiness Scale Conventional Self vs Physician Administration Mario Francesco Damiani, MD; Vitaliano Nicola Quaranta, MD; Vito Antonio Falcone, MD; Felice Gadaleta, MD; Michele Maiellari, MD; Teresa Ranieri, MD; Francesco Fanfulla, MD; Pierluigi Carratù, MD, PhD; and Onofrio Resta, MD, FCCP
Background: The Epworth Sleepiness Scale (ESS) is a simple, self-administered questionnaire that provides a measurement of the subject’s level of daytime sleepiness, and is widely used for patients with obstructive sleep apnea (OSA). Some works undermined its accuracy. The aim of this study was to compare self-administered ESS scores to physician-administered scores in a sample of patients with suspicion of OSA. Methods: Patients were randomly divided into two groups: group 1, or the self-administered group (n 5 113); and group 2, or the physician-administered group (n 5 112). Patients in group 1 were asked to complete the ESS in the traditional way; in group 2, the ESS was administered by a sleep-medicine physician. Subjects in both groups underwent diagnostic in-laboratory portable monitoring (PM) within 1 week’s time. Results: The percentage of questionnaires properly completed was significantly different between groups: 77% (87 of 113) in the group 1 vs 100% (112 of 112) in the group 2 (P 5 .00). Scores obtained when a physician administered the questionnaire (ESSp) were higher than those when the ESS was self administered (ESSs) (ESSp:12.09 ⫾ 4.1 vs ESSs:10.37 ⫾ 5.49; P 5 .01). The ESSp was more highly correlated with apnea-hypopnea index and oxygen desaturation index than the ESSs. Conclusions: Our results lead us to consider the physician-administered ESS to be more accurate than the traditional ESS; thus, our suggestion is to validate this new method of administration. CHEST 2013; 143(6):1569–1575 Abbreviations: AHI 5 apnea-hypopnea index; CSD 5 chronic sleep duration; ESS 5 Epworth Sleepiness Scale; ODI 5 oxygen desaturation index; OSA 5 obstructive sleep apnea; PM 5 portable monitoring; TST90 5 oxyhemoglobin saturation , 90%
Epworth Sleepiness Scale (ESS) is a simple, Theself-administered questionnaire that provides a measurement of the subject’s level of daytime sleepiness.1 It was proposed by Johns2 in 1991 and is widely used
Manuscript received September 3, 2012; revision accepted February 1, 2013. Affiliations: From the Institute of Respiratory Disease (Drs Damiani, Quaranta, Falcone, Gadaleta, Maiellari, Ranieri, Carratù, and Resta), University of Bari, Bari, Italy; Hospital “Salvatore Maugeri” (Dr Fanfulla), Pavia, Italy. Funding/Support: The authors report to CHEST that no funding or other support was received for this study. Correspondence to: Mario Francesco Damiani, MD, Piazza Giulio Cesare 11, Bari, Italy; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2174 journal.publications.chestnet.org
for patients with obstructive sleep apnea (OSA),3 but also for narcolepsy,4 idiopathic hypersomnia,5 insomnia,6 and other neurologic diseases.7 The ESS consists of eight specific situations for which patients evaluate their likelihood of falling asleep on a scale of 0 to 3.2 The ESS has been translated in many languages, including Italian,8 Portuguese,9 Spanish,10 Japanese,11 Chinese,12 and Norwegian.13 Nevertheless, some works undermined its accuracy. Resta et al14 demonstrated that, independently of OSA, severe obesity may be associated with excessive daytime sleepiness, as measured by ESS. Nguyen et al15 evaluated clinical reproducibility of the ESS, and demonstrated that the ESS score has a broad spectrum of variability when administered sequentially to a population with suspicion of sleep apnea. In another study, patient and bed-partner CHEST / 143 / 6 / JUNE 2013
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ESS scores were compared, and it was observed that patients rated their sleepiness lower than their partners did.16 To date, there are still conflicting data regarding the correlation between the ESS and polysomnographic parameters. On one hand, some authors found a significant correlation with apnea-hypopnea index (AHI), total sleep time with oxyhemoglobin saturation below 90% (TST90), and arousal index17-19; on the other hand, it was demonstrated that the ESS is only marginally useful in predicting the occurrence of OSA.20,21 All these reasons led to proposed changes to this questionnaire to improve both its accuracy and its usefulness.22 As noted, this questionnaire has been established to be self administered,2 and to our knowledge, scores obtained via physicians have not been extensively studied in the literature. The aim of this study was to compare scores of self-administered ESS to physician-administered ESS in a sample of patients with suspicion of OSA.
The study was approved by the institutional review board of Bari University General Hospital and carried out in accordance with the principles of the Helsinki Declaration. All patients gave prior written informed consent to take part in the study. The registration number is 4056 (www.policlinico.ba.it). Methods
Between November 2010 and June 2012, we enrolled 225 patients who were referred for their sleep study for suspicion of OSA to our Sleep Centre at the Institute of Respiratory Diseases (University of Bari, Italy). The inclusion criteria were: (1) age ⱖ 18 years; (2) no previous evaluation for suspected OSA; (3) no shift-workers; (4) absence of psychiatric (eg, schizophrenia, nonspecific psychosis, depression) and neurologic (eg, insomnia, narcolepsy) comorbidities, and related drugs; and (5) absence of periodic limb-movement disorder.
The ESS is an eight-item questionnaire that assesses the severity of daytime sleepiness in various situations.1 For each of the eight questions, the patient is required to rate his or her likelihood of sleepiness from 0 to 3 (0 5 no, 1 5 slight, 2 5 moderate, 3 5 high chance of dozing). The total score is marked out of a maximum of 24, and a score . 10 is considered to be abnormal and indicative of excessive daytime sleepiness. The items are as follows: (1) sitting and reading; (2) watching television; (3) sitting inactive in a public place (eg, a theater or a meeting); (4) as a passenger in a car for an hour without a break; (5) lying down to rest in the afternoon when circumstances permit; (6) sitting and talking to someone; (7) sitting quietly after lunch without alcohol; and (8) in a car, while stopped for a few minutes in traffic.1,2 In this study, the questionnaire was self- or physician-administered using the Italian version of the ESS.8 The portable monitor used in laboratory (Somtè Compumedics Inc) recorded the following signals: nasal airflow, thoracic and abdominal movements, arterial oxygen saturation, ECG, body position, and snoring. PM recordings were interpreted by two sleep-medicine physicians blinded to ESS scores, according to Italian Association of Hospital Pulmonologists guidelines.23 An AHI ⱖ 5 was necessary to diagnose OSA.24 Apnea was defined as a decrease in airflow of at least 80% for ⱖ 10 s, and hypopnea was defined as a 50% decrease of flow amplitude or 30% followed by oxygen desaturation . 3%. Sleep time was obtained as follows: Each patient filled out a sleep diary, and hours in which patients reported they had not slept were subtracted from total hours of recording time. Outpatient sleep parameters were derived from the presumed sleep time (or useful recording time). PM was not considered reliable if the quality of one of the main signals (oxygen saturation, thoracic/abdominal movements, nasal airflow) was poor for . 20% of the recording time.
Study Design
Statistical Analysis
This work was a randomized, prospective study with two parallel arms. The randomization assignments were computer generated using a block permutation method to select one of the two diagnostic alternatives. Randomization was performed by the staff of our hospital, who had no direct participation in the study. Patients were randomly divided into two groups: group 1, or the selfadministered group (n 5 113); and group 2, or the physicianadministered group (n 5 112). Patients in group 1 were asked to complete the ESS in the traditional way: They were left alone in the waiting room and answered the questionnaire without any help from a physician or family members. In group 2, the ESS was administered by two sleep-medicine physicians who read aloud and explained the questions to the patients and filled out the questionnaire for the patient according to their answers; the physicians did not influence the answers given by the patients, but ensured that answers were definite. The two physicians who administered the questionnaire were unaware of the patient’s medical history and complaints, which were collected by a third physician. People who completed the self-administered ESS got a standardized set of instructions by a physician blind to physicianadministered ESS scores. All questionnaires were administered between 11:00 am and 1:00 pm. Subjects in both groups underwent diagnostic, in-laboratory, portable monitoring (PM) within 1 week’s time of completing the questionnaire.
Data are presented as mean ⫾ SD unless otherwise indicated. Differences between two groups were analyzed by a Student t test for independent samples. Differences among three groups were analyzed using analysis of variance. Correlations were described with the Pearson correlation coefficient (r). Differences among correlation coefficients were calculated using the Fisher transformation. A value of P , .05 was considered statistically significant. The analyses were made using STATISTICA version 6.1 software (StatSoft Inc).
Materials and Methods Patients
Results Figure 1 shows the study flowchart. We enrolled 225 patients in this study. In the group 1, 23% (26 of 113) of subjects did not properly complete the ESS: Nine patients answered using “yes” or “no,” rather than indicating numbers, eight put a cross against the questions rather than scoring them, six left questions blank, and three stated that they could not read. In group 2, the questionnaire was successfully completed in all cases. Therefore, the percentage of questionnaires
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Original Research
Figure 1. Study flowchart. ESS 5 Epworth Sleepiness Scale; ESSs 5 self-administered Epworth Sleepiness Scale; ESSp 5 physician-administered Epworth Sleepiness Scale; OSA 5 obstructive sleep apnea; PM 5 portable monitoring.
properly completed was significantly different between groups: 77% (87 of 113) in group 1 vs 100% (112 of 112) in the group2 (P 5 .00). The comparison of the scores obtained with the two methods of administration, and the correlation with the sleep parameters were performed on the remaining 199 patients. Demo-
graphic characteristics and baseline sleep parameters of the population finally studied are shown in Table 1, with no differences between groups. The characteristics of patients who did not properly complete the questionnaire were similar to those who successfully completed it.
Table 1—Demographic Characteristics and Baseline Sleep Parameters of the Study Population Characteristics Subjects, No. Sex, male (female), No. Age, y BMI, kg/m2 Neck circumference, cm Waist circumference, cm AHI score/h OSA subjects, No. (%) ODI/h TST90, % Sao2 nadir, %
All Patients
NA-ESSsa
Group 1b
Group 2c
P Value
225 191 (34) 52.44 ⫾ 14.22 29.53 ⫾ 4.63 40.06 ⫾ 3.94 107.72 ⫾ 13.92 30.28 ⫾ 24.46 187 (83) 28.08 ⫾ 22.92 27.37 ⫾ 22.79 81.39 ⫾ 7.01
26 23 (3) 51.15 ⫾ 10.24 30.50 ⫾ 3.88 40.57 ⫾ 2.56 110.46 ⫾ 11.77 31.46 ⫾ 22.26 22 (84) 29.93 ⫾ 21.1 27.81 ⫾ 25.75 81.42 ⫾ 6.25
87 75 (12) 53.28 ⫾ 13.83 28.96 ⫾ 4.1 39.54 ⫾ 3.82 106.20 ⫾ 13.24 29.20 ⫾ 22.63 73 (84) 26.79 ⫾ 20.83 24.75 ⫾ 17.67 81.57 ⫾ 6.73
112 93 (19) 52.08 ⫾ 15.34 29.75 ⫾ 5.09 40.35 ⫾ 4.25 108.27 ⫾ 14.83 30.84 ⫾ 26.23 92 (82) 28.65 ⫾ 24.93 29.31 ⫾ 25.44 81.24 ⫾ 7.43
.71 .74 .25 .27 .33 .86 .92 .77 .37 .94
Data are presented as mean values ⫾ SD unless otherwise indicated. AHI 5 apnea-hypopnea index; NA 5 not assessable; ODI 5 oxygen desaturation index; OSA 5 obstructive sleep apnea; TST90 5 total sleep time with oxyhemoglobin saturation , 90%, Sao2 5 arterial oxygen saturation. aAnalysis of variance was used to compare NA-ESSs, group 1, and group 2. bSelf-administered ESS. cPhysician-reported ESS. journal.publications.chestnet.org
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Results for the self-administered ESS (ESSs) and the physician-administered ESS (ESSp) are given in Figure 2. Scores obtained by the ESSp were higher than those for the ESSs (12.09 ⫾ 4.1 vs 10.37 ⫾ 5.49; P 5 .01). Table 2 shows correlation coefficients of ESSs and ESSp with OSA variables. The ESSs was significantly but weakly correlated to AHI (r 5 0.21; P 5 .04), oxygen desaturation index (ODI) (r 5 0.22; P 5 .03), and TST90 (r 5 0.27; P 5 .01); no significant correlation was found between the ESSs and arterial oxygen saturation nadir (r 5 20.19; P 5 .07). The ESSp was significantly correlated to all sleep parameters, and an increased correlation was observed between OSA variables and ESS, from ESSs to ESSp: The increase in r between ESS and AHI, from 0.21 in the ESSs to 0.51 in the ESSp, was significant (P 5 .02); a significantly higher correlation was also observed with ODI, from 0.22 to 0.49 (P 5 .04). The increase of the correlation coefficient between the questionnaire and the other sleep parameters was not significant between the two groups. Each question was examined separately to determine whether any one question was predominantly responsible for the difference between the two scores; no significant differences were found (Table 3). Moreover, there were not specific questions that were particularly highly or poorly correlated with sleep parameters (data not shown). This result led us to consider that none of the eight questions was predominantly responsible for the significant difference observed between the ESSs and ESSp groups. Discussion In this study, we compared scores of the traditional ESS to those obtained by physician-administration in a sample of patients with suspected OSA. It was found that ESSp scores were significantly higher than ESSs scores; moreover, the ESSp showed a stronger correla-
Table 2—Correlation Coefficients of ESSs and ESSp With OSA Variables Variables
ESSs
ESSp
P Value
AHI ODI TST90 Sao2 nadir
r (P Value) 0.21 (0.04) 0.22 (0.03) 0.27 (0.01) 20.19 (0.07)
r (P Value) 0.51 (0.00) 0.49 (0.00) 0.47 (0.00) 20.44 (0.00)
.02 .04 .1 .06
See Table 1 legend for expansion of abbreviations.
tion with sleep parameters, compared with the ESSs. To date, only one study, to our knowledge, has been conducted in which the two aforesaid methods of administration have been compared. Kaminska et al25 evaluated 188 patients with suspicion of OSA, and observed that ESSs scores were significantly higher than ESSp scores. In addition, Ugur et al26 assessed the possible role of nurses in administration of this questionnaire; they found no significant differences between the self- and the nurse-administered ESS. The findings of the aforementioned studies disagree with ours. It is important, however, to underline a methodologic difference between our experience and the two previously cited works that may have influenced the final results: neither Kaminska et al25 nor Ugur et al26 used randomization. In those studies, the same patients first completed the questionnaire by themselves, and then again subsequently with the help of a physician or a nurse. Our work was a randomized trial, with the ESS self administered in group 1, and physician administered in group 2; in this manner, we prevented the ESSs from influencing the answers to the ESSp. The observed difference between ESSs and ESSp scores may be due to patients’ misinterpretation of the questions and/or the answer options. Therefore, patients may provide inaccurate answers when performing the test by themselves. Otherwise, talking with a sleep-medicine physician can be useful for patients to better understand the meaning of each questionand-answer option to obtain more accurate data. Table 3—Comparison for Each Question Between ESSs and ESSp ESS Question
Figure 2. Results for the self-administered and the physicianadministered ESS. *P , .05. See Figure 1 legend for expansion of abbreviations.
Reading Watching television In public As a passenger Lying down Talking Sitting quietly In traffic
ESSs
ESSp
P Value
1.18 ⫾ 1.17 1.80 ⫾ 1.19 1.10 ⫾ 1.13 1.34 ⫾ 1.21 1.71 ⫾ 1.22 0.62 ⫾ 1.04 1.95 ⫾ 1.13 0.64 ⫾ 1.10
1.46 ⫾ 1.23 1.96 ⫾ 1.13 1.3 ⫾ 1.22 1.45 ⫾ 1.20 1.99 ⫾ 1.15 0.82 ⫾ 1.1 2.19 ⫾ 1.02 0.73 ⫾ 1.03
.10 .33 .23 .52 .09 .19 .11 .55
Data are presented as mean values ⫾ SD unless otherwise indicated. See Table 1 legend for expansion of abbreviations.
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Many studies have evaluated the correlation between excessive daytime sleepiness as measured by the ESS, and sleep parameters, with no agreement among their results.17,20,27 Conflicting data emerged even when the ESS was sequentially administered to a same-study population.28 The controversy in the literature regarding this correlation suggests that it is unlikely that the traditional ESS plays a key role in detection of apneas. In the present study, we found a significant but weak correlation between ESSs and AHI (r 5 0.21), similar to some previous studies25,28; on the other hand, a correlation coefficient significantly higher was observed with the ESSp (r 5 0.51). To our knowledge, this is the first study that measured the correlation between the ESSp and AHI. In this regard, it is important to underline that the correlation that we found using the ESSp is stronger than the one demonstrated in any other previous study using the traditional test. It also is important to point out that the correlations with sleep parameters were examined to support the relevance of the differences between the scores obtained by the two methods of ESS administration, especially in the context of the research environment where data linking the ESS to OSA severity has generally been made based on ESSs data.17,20 Indeed, the ESS was developed only to assess sleepiness1; thus, it would be unrealistic to assume that this questionnaire may be useful to distinguish between patients with OSA and those without, since diagnosis of OSA must be established by objective testing; the two accepted methods of objective testing are in-laboratory polysomnography, and PM.29 Therefore, our results suggest that the ESSp may be both a more accurate and useful tool than the ESSs for a preliminary clinical evaluation in a sample of patients with suspicion of OSA. The prerequisite for the ESS to be helpful in the management of subjects with suspected OSA is the successful completion of the questionnaire. In this regard, it is worth highlighting that in our study, 23% of patients made errors when completing the test by themselves, such that the test was not valid. Errors were mainly due to a failure to interpret correctly either the questions or the answer options. Otherwise, in group 2, the ESS was successfully completed in all cases. It is likely that the difference found between the two groups was due to the presence in group 2 of a sleep-medicine physician who explained and clarified the meaning of both the questions and the answer options; in this manner, patients avoided interpretation errors. The first step in OSA diagnosis is represented by a clinical assessment of the patient.30 On the basis of this preliminary evaluation, the physician establishes whether it is necessary for the subject to undergo an overnight polysomnography, which is the gold stanjournal.publications.chestnet.org
dard for diagnosing OSA.31 Therefore, the accuracy of the ESS should be ensured, since it has an important role in clinical evaluation. Our results indicate the ESSp to be more accurate than the traditional ESS. On one hand, it should be remarked that the beauty of the ESS is that it can be self administered and, therefore, requires no physician time; on the other hand, in our opinion, it is useless and misleading to use a test that is not accurate. Furthermore, it is conceivable that with the help of a sleep-medicine physician, the questionnaire may be completed more quickly than by a patient who reads it for the first time and has to face a series of difficulties related to the understanding and the interpretation of both questions and answers. On that account, the ESSp may be considered as practical both in research and clinical situations. Thus, our suggestion is to validate this new method of administration. In the present study, some important limitations need to be considered. First, sleep parameters were obtained in absence of objective sleep time; although this limit is insurmountable due to the obvious impossibility of measuring these parameters in absence of electrophysiologic signals, we calculated the polygraphic indices following the recommended method for cardiorespiratory monitoring.32 Second, chronic sleep duration (CSD) was not assessed and, therefore, there is the possibility that there were between-group differences with regard to CSD, such that ESSs and ESSp scores differed on this basis rather than, or in addition to, the manner of instrument administration. However, the exclusion from this study of several conditions that commonly affect CSD, such as shift work,33 psychiatric and neurologic diseases,34 and related drugs,34 may, to some extent, counterbalance this limitation. Third, the study conditions regarding the ESSs may not reflect all clinical environments. Indeed, in our study, participants in group 1 were left alone in the waiting room and were not permitted to ask questions after beginning the questionnaire; we suspect that most clinical environments allow confused patients to ask questions. It is important, however, to underline that our study stems from the desire to make evident and clear what, to date, is only a suspicion: The questionnaire completed with the help of a physician is more accurate than the ESSs. Another limitation of this study is represented by a small sample size. Therefore, larger trials are requested to confirm our finding. In addition, it would be of interest to know if longitudinal reproducibility differs between ESSs and ESSp. In conclusion, we demonstrated that the ESSp is more accurate than the ESSs. The presence of a sleepmedicine physician ensures the successful completion of the questionnaire. Larger trials are needed to validate this new method of administration. CHEST / 143 / 6 / JUNE 2013
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Acknowledgments Author contributions: Dr Damiani had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Dr Damiani: contributed to the study design, data collection and analysis, preparation of the manuscript, and served as principal author. Dr Quaranta: contributed to the study design, preparation of the manuscript, and approval of the final version of the manuscript. Dr Falcone: contributed to the study design, data collection, preparation of the manuscript, and approval of the final version of the manuscript. Dr Gadaleta: contributed to data collection, preparation of the manuscript, and approval of the final version of the manuscript. Dr Maiellari: contributed to data analysis and preparation of the manuscript. Dr Ranieri: contributed to data collection, preparation of the manuscript, and approval of the final version of the manuscript. Dr Fanfulla: contributed to data analysis, preparation of the manuscript, and approval of the final version of the manuscript. Dr Carratù: contributed to preparation of the manuscript and approval of the final version of the manuscript. Dr Resta: contributed to the study design; review and interpretation of data; review and revision of the manuscript; and approval of the final version of the manuscript. Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
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Original Research SLEEP DISORDERS
The Epworth Sleepiness Scale Conventional Self vs Physician Administration Mario Francesco Damiani, MD; Vitaliano Nicola Quaranta, MD; Vito Antonio Falcone, MD; Felice Gadaleta, MD; Michele Maiellari, MD; Teresa Ranieri, MD; Francesco Fanfulla, MD; Pierluigi Carratù, MD, PhD; and Onofrio Resta, MD, FCCP
Background: The Epworth Sleepiness Scale (ESS) is a simple, self-administered questionnaire that provides a measurement of the subject’s level of daytime sleepiness, and is widely used for patients with obstructive sleep apnea (OSA). Some works undermined its accuracy. The aim of this study was to compare self-administered ESS scores to physician-administered scores in a sample of patients with suspicion of OSA. Methods: Patients were randomly divided into two groups: group 1, or the self-administered group (n 5 113); and group 2, or the physician-administered group (n 5 112). Patients in group 1 were asked to complete the ESS in the traditional way; in group 2, the ESS was administered by a sleep-medicine physician. Subjects in both groups underwent diagnostic in-laboratory portable monitoring (PM) within 1 week’s time. Results: The percentage of questionnaires properly completed was significantly different between groups: 77% (87 of 113) in the group 1 vs 100% (112 of 112) in the group 2 (P 5 .00). Scores obtained when a physician administered the questionnaire (ESSp) were higher than those when the ESS was self administered (ESSs) (ESSp:12.09 ⫾ 4.1 vs ESSs:10.37 ⫾ 5.49; P 5 .01). The ESSp was more highly correlated with apnea-hypopnea index and oxygen desaturation index than the ESSs. Conclusions: Our results lead us to consider the physician-administered ESS to be more accurate than the traditional ESS; thus, our suggestion is to validate this new method of administration. CHEST 2013; 143(6):1569–1575 Abbreviations: AHI 5 apnea-hypopnea index; CSD 5 chronic sleep duration; ESS 5 Epworth Sleepiness Scale; ODI 5 oxygen desaturation index; OSA 5 obstructive sleep apnea; PM 5 portable monitoring; TST90 5 oxyhemoglobin saturation , 90%
Epworth Sleepiness Scale (ESS) is a simple, Theself-administered questionnaire that provides a measurement of the subject’s level of daytime sleepiness.1 It was proposed by Johns2 in 1991 and is widely used
Manuscript received September 3, 2012; revision accepted February 1, 2013. Affiliations: From the Institute of Respiratory Disease (Drs Damiani, Quaranta, Falcone, Gadaleta, Maiellari, Ranieri, Carratù, and Resta), University of Bari, Bari, Italy; Hospital “Salvatore Maugeri” (Dr Fanfulla), Pavia, Italy. Funding/Support: The authors report to CHEST that no funding or other support was received for this study. Correspondence to: Mario Francesco Damiani, MD, Piazza Giulio Cesare 11, Bari, Italy; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2174 journal.publications.chestnet.org
for patients with obstructive sleep apnea (OSA),3 but also for narcolepsy,4 idiopathic hypersomnia,5 insomnia,6 and other neurologic diseases.7 The ESS consists of eight specific situations for which patients evaluate their likelihood of falling asleep on a scale of 0 to 3.2 The ESS has been translated in many languages, including Italian,8 Portuguese,9 Spanish,10 Japanese,11 Chinese,12 and Norwegian.13 Nevertheless, some works undermined its accuracy. Resta et al14 demonstrated that, independently of OSA, severe obesity may be associated with excessive daytime sleepiness, as measured by ESS. Nguyen et al15 evaluated clinical reproducibility of the ESS, and demonstrated that the ESS score has a broad spectrum of variability when administered sequentially to a population with suspicion of sleep apnea. In another study, patient and bed-partner CHEST / 143 / 6 / JUNE 2013
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ESS scores were compared, and it was observed that patients rated their sleepiness lower than their partners did.16 To date, there are still conflicting data regarding the correlation between the ESS and polysomnographic parameters. On one hand, some authors found a significant correlation with apnea-hypopnea index (AHI), total sleep time with oxyhemoglobin saturation below 90% (TST90), and arousal index17-19; on the other hand, it was demonstrated that the ESS is only marginally useful in predicting the occurrence of OSA.20,21 All these reasons led to proposed changes to this questionnaire to improve both its accuracy and its usefulness.22 As noted, this questionnaire has been established to be self administered,2 and to our knowledge, scores obtained via physicians have not been extensively studied in the literature. The aim of this study was to compare scores of self-administered ESS to physician-administered ESS in a sample of patients with suspicion of OSA.
The study was approved by the institutional review board of Bari University General Hospital and carried out in accordance with the principles of the Helsinki Declaration. All patients gave prior written informed consent to take part in the study. The registration number is 4056 (www.policlinico.ba.it). Methods
Between November 2010 and June 2012, we enrolled 225 patients who were referred for their sleep study for suspicion of OSA to our Sleep Centre at the Institute of Respiratory Diseases (University of Bari, Italy). The inclusion criteria were: (1) age ⱖ 18 years; (2) no previous evaluation for suspected OSA; (3) no shift-workers; (4) absence of psychiatric (eg, schizophrenia, nonspecific psychosis, depression) and neurologic (eg, insomnia, narcolepsy) comorbidities, and related drugs; and (5) absence of periodic limb-movement disorder.
The ESS is an eight-item questionnaire that assesses the severity of daytime sleepiness in various situations.1 For each of the eight questions, the patient is required to rate his or her likelihood of sleepiness from 0 to 3 (0 5 no, 1 5 slight, 2 5 moderate, 3 5 high chance of dozing). The total score is marked out of a maximum of 24, and a score . 10 is considered to be abnormal and indicative of excessive daytime sleepiness. The items are as follows: (1) sitting and reading; (2) watching television; (3) sitting inactive in a public place (eg, a theater or a meeting); (4) as a passenger in a car for an hour without a break; (5) lying down to rest in the afternoon when circumstances permit; (6) sitting and talking to someone; (7) sitting quietly after lunch without alcohol; and (8) in a car, while stopped for a few minutes in traffic.1,2 In this study, the questionnaire was self- or physician-administered using the Italian version of the ESS.8 The portable monitor used in laboratory (Somtè Compumedics Inc) recorded the following signals: nasal airflow, thoracic and abdominal movements, arterial oxygen saturation, ECG, body position, and snoring. PM recordings were interpreted by two sleep-medicine physicians blinded to ESS scores, according to Italian Association of Hospital Pulmonologists guidelines.23 An AHI ⱖ 5 was necessary to diagnose OSA.24 Apnea was defined as a decrease in airflow of at least 80% for ⱖ 10 s, and hypopnea was defined as a 50% decrease of flow amplitude or 30% followed by oxygen desaturation . 3%. Sleep time was obtained as follows: Each patient filled out a sleep diary, and hours in which patients reported they had not slept were subtracted from total hours of recording time. Outpatient sleep parameters were derived from the presumed sleep time (or useful recording time). PM was not considered reliable if the quality of one of the main signals (oxygen saturation, thoracic/abdominal movements, nasal airflow) was poor for . 20% of the recording time.
Study Design
Statistical Analysis
This work was a randomized, prospective study with two parallel arms. The randomization assignments were computer generated using a block permutation method to select one of the two diagnostic alternatives. Randomization was performed by the staff of our hospital, who had no direct participation in the study. Patients were randomly divided into two groups: group 1, or the selfadministered group (n 5 113); and group 2, or the physicianadministered group (n 5 112). Patients in group 1 were asked to complete the ESS in the traditional way: They were left alone in the waiting room and answered the questionnaire without any help from a physician or family members. In group 2, the ESS was administered by two sleep-medicine physicians who read aloud and explained the questions to the patients and filled out the questionnaire for the patient according to their answers; the physicians did not influence the answers given by the patients, but ensured that answers were definite. The two physicians who administered the questionnaire were unaware of the patient’s medical history and complaints, which were collected by a third physician. People who completed the self-administered ESS got a standardized set of instructions by a physician blind to physicianadministered ESS scores. All questionnaires were administered between 11:00 am and 1:00 pm. Subjects in both groups underwent diagnostic, in-laboratory, portable monitoring (PM) within 1 week’s time of completing the questionnaire.
Data are presented as mean ⫾ SD unless otherwise indicated. Differences between two groups were analyzed by a Student t test for independent samples. Differences among three groups were analyzed using analysis of variance. Correlations were described with the Pearson correlation coefficient (r). Differences among correlation coefficients were calculated using the Fisher transformation. A value of P , .05 was considered statistically significant. The analyses were made using STATISTICA version 6.1 software (StatSoft Inc).
Materials and Methods Patients
Results Figure 1 shows the study flowchart. We enrolled 225 patients in this study. In the group 1, 23% (26 of 113) of subjects did not properly complete the ESS: Nine patients answered using “yes” or “no,” rather than indicating numbers, eight put a cross against the questions rather than scoring them, six left questions blank, and three stated that they could not read. In group 2, the questionnaire was successfully completed in all cases. Therefore, the percentage of questionnaires
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Original Research
Figure 1. Study flowchart. ESS 5 Epworth Sleepiness Scale; ESSs 5 self-administered Epworth Sleepiness Scale; ESSp 5 physician-administered Epworth Sleepiness Scale; OSA 5 obstructive sleep apnea; PM 5 portable monitoring.
properly completed was significantly different between groups: 77% (87 of 113) in group 1 vs 100% (112 of 112) in the group2 (P 5 .00). The comparison of the scores obtained with the two methods of administration, and the correlation with the sleep parameters were performed on the remaining 199 patients. Demo-
graphic characteristics and baseline sleep parameters of the population finally studied are shown in Table 1, with no differences between groups. The characteristics of patients who did not properly complete the questionnaire were similar to those who successfully completed it.
Table 1—Demographic Characteristics and Baseline Sleep Parameters of the Study Population Characteristics Subjects, No. Sex, male (female), No. Age, y BMI, kg/m2 Neck circumference, cm Waist circumference, cm AHI score/h OSA subjects, No. (%) ODI/h TST90, % Sao2 nadir, %
All Patients
NA-ESSsa
Group 1b
Group 2c
P Value
225 191 (34) 52.44 ⫾ 14.22 29.53 ⫾ 4.63 40.06 ⫾ 3.94 107.72 ⫾ 13.92 30.28 ⫾ 24.46 187 (83) 28.08 ⫾ 22.92 27.37 ⫾ 22.79 81.39 ⫾ 7.01
26 23 (3) 51.15 ⫾ 10.24 30.50 ⫾ 3.88 40.57 ⫾ 2.56 110.46 ⫾ 11.77 31.46 ⫾ 22.26 22 (84) 29.93 ⫾ 21.1 27.81 ⫾ 25.75 81.42 ⫾ 6.25
87 75 (12) 53.28 ⫾ 13.83 28.96 ⫾ 4.1 39.54 ⫾ 3.82 106.20 ⫾ 13.24 29.20 ⫾ 22.63 73 (84) 26.79 ⫾ 20.83 24.75 ⫾ 17.67 81.57 ⫾ 6.73
112 93 (19) 52.08 ⫾ 15.34 29.75 ⫾ 5.09 40.35 ⫾ 4.25 108.27 ⫾ 14.83 30.84 ⫾ 26.23 92 (82) 28.65 ⫾ 24.93 29.31 ⫾ 25.44 81.24 ⫾ 7.43
.71 .74 .25 .27 .33 .86 .92 .77 .37 .94
Data are presented as mean values ⫾ SD unless otherwise indicated. AHI 5 apnea-hypopnea index; NA 5 not assessable; ODI 5 oxygen desaturation index; OSA 5 obstructive sleep apnea; TST90 5 total sleep time with oxyhemoglobin saturation , 90%, Sao2 5 arterial oxygen saturation. aAnalysis of variance was used to compare NA-ESSs, group 1, and group 2. bSelf-administered ESS. cPhysician-reported ESS. journal.publications.chestnet.org
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Results for the self-administered ESS (ESSs) and the physician-administered ESS (ESSp) are given in Figure 2. Scores obtained by the ESSp were higher than those for the ESSs (12.09 ⫾ 4.1 vs 10.37 ⫾ 5.49; P 5 .01). Table 2 shows correlation coefficients of ESSs and ESSp with OSA variables. The ESSs was significantly but weakly correlated to AHI (r 5 0.21; P 5 .04), oxygen desaturation index (ODI) (r 5 0.22; P 5 .03), and TST90 (r 5 0.27; P 5 .01); no significant correlation was found between the ESSs and arterial oxygen saturation nadir (r 5 20.19; P 5 .07). The ESSp was significantly correlated to all sleep parameters, and an increased correlation was observed between OSA variables and ESS, from ESSs to ESSp: The increase in r between ESS and AHI, from 0.21 in the ESSs to 0.51 in the ESSp, was significant (P 5 .02); a significantly higher correlation was also observed with ODI, from 0.22 to 0.49 (P 5 .04). The increase of the correlation coefficient between the questionnaire and the other sleep parameters was not significant between the two groups. Each question was examined separately to determine whether any one question was predominantly responsible for the difference between the two scores; no significant differences were found (Table 3). Moreover, there were not specific questions that were particularly highly or poorly correlated with sleep parameters (data not shown). This result led us to consider that none of the eight questions was predominantly responsible for the significant difference observed between the ESSs and ESSp groups. Discussion In this study, we compared scores of the traditional ESS to those obtained by physician-administration in a sample of patients with suspected OSA. It was found that ESSp scores were significantly higher than ESSs scores; moreover, the ESSp showed a stronger correla-
Table 2—Correlation Coefficients of ESSs and ESSp With OSA Variables Variables
ESSs
ESSp
P Value
AHI ODI TST90 Sao2 nadir
r (P Value) 0.21 (0.04) 0.22 (0.03) 0.27 (0.01) 20.19 (0.07)
r (P Value) 0.51 (0.00) 0.49 (0.00) 0.47 (0.00) 20.44 (0.00)
.02 .04 .1 .06
See Table 1 legend for expansion of abbreviations.
tion with sleep parameters, compared with the ESSs. To date, only one study, to our knowledge, has been conducted in which the two aforesaid methods of administration have been compared. Kaminska et al25 evaluated 188 patients with suspicion of OSA, and observed that ESSs scores were significantly higher than ESSp scores. In addition, Ugur et al26 assessed the possible role of nurses in administration of this questionnaire; they found no significant differences between the self- and the nurse-administered ESS. The findings of the aforementioned studies disagree with ours. It is important, however, to underline a methodologic difference between our experience and the two previously cited works that may have influenced the final results: neither Kaminska et al25 nor Ugur et al26 used randomization. In those studies, the same patients first completed the questionnaire by themselves, and then again subsequently with the help of a physician or a nurse. Our work was a randomized trial, with the ESS self administered in group 1, and physician administered in group 2; in this manner, we prevented the ESSs from influencing the answers to the ESSp. The observed difference between ESSs and ESSp scores may be due to patients’ misinterpretation of the questions and/or the answer options. Therefore, patients may provide inaccurate answers when performing the test by themselves. Otherwise, talking with a sleep-medicine physician can be useful for patients to better understand the meaning of each questionand-answer option to obtain more accurate data. Table 3—Comparison for Each Question Between ESSs and ESSp ESS Question
Figure 2. Results for the self-administered and the physicianadministered ESS. *P , .05. See Figure 1 legend for expansion of abbreviations.
Reading Watching television In public As a passenger Lying down Talking Sitting quietly In traffic
ESSs
ESSp
P Value
1.18 ⫾ 1.17 1.80 ⫾ 1.19 1.10 ⫾ 1.13 1.34 ⫾ 1.21 1.71 ⫾ 1.22 0.62 ⫾ 1.04 1.95 ⫾ 1.13 0.64 ⫾ 1.10
1.46 ⫾ 1.23 1.96 ⫾ 1.13 1.3 ⫾ 1.22 1.45 ⫾ 1.20 1.99 ⫾ 1.15 0.82 ⫾ 1.1 2.19 ⫾ 1.02 0.73 ⫾ 1.03
.10 .33 .23 .52 .09 .19 .11 .55
Data are presented as mean values ⫾ SD unless otherwise indicated. See Table 1 legend for expansion of abbreviations.
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Many studies have evaluated the correlation between excessive daytime sleepiness as measured by the ESS, and sleep parameters, with no agreement among their results.17,20,27 Conflicting data emerged even when the ESS was sequentially administered to a same-study population.28 The controversy in the literature regarding this correlation suggests that it is unlikely that the traditional ESS plays a key role in detection of apneas. In the present study, we found a significant but weak correlation between ESSs and AHI (r 5 0.21), similar to some previous studies25,28; on the other hand, a correlation coefficient significantly higher was observed with the ESSp (r 5 0.51). To our knowledge, this is the first study that measured the correlation between the ESSp and AHI. In this regard, it is important to underline that the correlation that we found using the ESSp is stronger than the one demonstrated in any other previous study using the traditional test. It also is important to point out that the correlations with sleep parameters were examined to support the relevance of the differences between the scores obtained by the two methods of ESS administration, especially in the context of the research environment where data linking the ESS to OSA severity has generally been made based on ESSs data.17,20 Indeed, the ESS was developed only to assess sleepiness1; thus, it would be unrealistic to assume that this questionnaire may be useful to distinguish between patients with OSA and those without, since diagnosis of OSA must be established by objective testing; the two accepted methods of objective testing are in-laboratory polysomnography, and PM.29 Therefore, our results suggest that the ESSp may be both a more accurate and useful tool than the ESSs for a preliminary clinical evaluation in a sample of patients with suspicion of OSA. The prerequisite for the ESS to be helpful in the management of subjects with suspected OSA is the successful completion of the questionnaire. In this regard, it is worth highlighting that in our study, 23% of patients made errors when completing the test by themselves, such that the test was not valid. Errors were mainly due to a failure to interpret correctly either the questions or the answer options. Otherwise, in group 2, the ESS was successfully completed in all cases. It is likely that the difference found between the two groups was due to the presence in group 2 of a sleep-medicine physician who explained and clarified the meaning of both the questions and the answer options; in this manner, patients avoided interpretation errors. The first step in OSA diagnosis is represented by a clinical assessment of the patient.30 On the basis of this preliminary evaluation, the physician establishes whether it is necessary for the subject to undergo an overnight polysomnography, which is the gold stanjournal.publications.chestnet.org
dard for diagnosing OSA.31 Therefore, the accuracy of the ESS should be ensured, since it has an important role in clinical evaluation. Our results indicate the ESSp to be more accurate than the traditional ESS. On one hand, it should be remarked that the beauty of the ESS is that it can be self administered and, therefore, requires no physician time; on the other hand, in our opinion, it is useless and misleading to use a test that is not accurate. Furthermore, it is conceivable that with the help of a sleep-medicine physician, the questionnaire may be completed more quickly than by a patient who reads it for the first time and has to face a series of difficulties related to the understanding and the interpretation of both questions and answers. On that account, the ESSp may be considered as practical both in research and clinical situations. Thus, our suggestion is to validate this new method of administration. In the present study, some important limitations need to be considered. First, sleep parameters were obtained in absence of objective sleep time; although this limit is insurmountable due to the obvious impossibility of measuring these parameters in absence of electrophysiologic signals, we calculated the polygraphic indices following the recommended method for cardiorespiratory monitoring.32 Second, chronic sleep duration (CSD) was not assessed and, therefore, there is the possibility that there were between-group differences with regard to CSD, such that ESSs and ESSp scores differed on this basis rather than, or in addition to, the manner of instrument administration. However, the exclusion from this study of several conditions that commonly affect CSD, such as shift work,33 psychiatric and neurologic diseases,34 and related drugs,34 may, to some extent, counterbalance this limitation. Third, the study conditions regarding the ESSs may not reflect all clinical environments. Indeed, in our study, participants in group 1 were left alone in the waiting room and were not permitted to ask questions after beginning the questionnaire; we suspect that most clinical environments allow confused patients to ask questions. It is important, however, to underline that our study stems from the desire to make evident and clear what, to date, is only a suspicion: The questionnaire completed with the help of a physician is more accurate than the ESSs. Another limitation of this study is represented by a small sample size. Therefore, larger trials are requested to confirm our finding. In addition, it would be of interest to know if longitudinal reproducibility differs between ESSs and ESSp. In conclusion, we demonstrated that the ESSp is more accurate than the ESSs. The presence of a sleepmedicine physician ensures the successful completion of the questionnaire. Larger trials are needed to validate this new method of administration. CHEST / 143 / 6 / JUNE 2013
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Acknowledgments Author contributions: Dr Damiani had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Dr Damiani: contributed to the study design, data collection and analysis, preparation of the manuscript, and served as principal author. Dr Quaranta: contributed to the study design, preparation of the manuscript, and approval of the final version of the manuscript. Dr Falcone: contributed to the study design, data collection, preparation of the manuscript, and approval of the final version of the manuscript. Dr Gadaleta: contributed to data collection, preparation of the manuscript, and approval of the final version of the manuscript. Dr Maiellari: contributed to data analysis and preparation of the manuscript. Dr Ranieri: contributed to data collection, preparation of the manuscript, and approval of the final version of the manuscript. Dr Fanfulla: contributed to data analysis, preparation of the manuscript, and approval of the final version of the manuscript. Dr Carratù: contributed to preparation of the manuscript and approval of the final version of the manuscript. Dr Resta: contributed to the study design; review and interpretation of data; review and revision of the manuscript; and approval of the final version of the manuscript. Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
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