Sleepiness in obstructive sleep apnea syndrome and simple snoring evaluated by the Epworth Sleepiness Scale

Sleep medicine literature is increasingly featuring data Fifty-four normal weight subjects matched to OSA patients concerning the Epworth Sleepiness Scale (ESS) as a measure for age and sex served as controls. These subjects were recruited of daytime sleepiness in clinical practice. We read with interest among friends of out-patients referring to our Institute of the paper by Olson et al. (1988) which, in contrast to Johns Neurology. They were healthy, drug-free nonsnorers. The (1993), finds that overall ESS score does not differ significantly control subjects did not have polysomnography. However they between obstructive sleep apnea syndrome (OSAS), snoring, all had a clinical and questionnaire based evaluation (Sleep and upper airways resistance syndrome in groups of patients. Disorders Questionnaire I of Douglass et al. 1994) aimed at Furthermore, Olson and colleagues failed to document any ruling out the existence of sleep disorders, namely OSA. Each significant relationship between ESS score and polygraphic of these subjects entered the study and provided the ESS data indexes of OSAS severity. They partly attribute the only if the subject’s raw score at subitems sleep-apnoea scale discrepancies between their findings and those of Johns to of SDQI fell in the normal range of the scale. differences in the pathways of referral of the patients, and in The mean global ESS score in OSAS patients was 11.7 (SD time and mode of scale completion. 4.6; range 4–20), in primary snoring patients 5.8 (SD 2.4; range Here we report ESS data collected from an Italian case series 2–11), and in healthy controls 4.4 (SD 2.8; range 0–11). The of OSAS, in which the snoring patient pathway of referral was mean overall ESS score is significantly higher in OSAS than similar to that in Olson’s experience, while time and mode of in simple snoring patients (P < 0.001 at one way  with completion of the scale were analogous to those adopted by post hoc Scheffè test). Johns. Overall ESS scores for the 54 OSAS patients were correlated The case series consisted of consecutive, non fee-paying adult with the RDI, nocturnal HbSaO2 nadir, age, and BMI by patients, referring to the Sleep Medicine Centre of the Institute means of the rho Spearman test (Table 1). of Neurology ‘C. Mondino’ between September 1997 and June A significant correlation was found between the ESS score 1998 on clinical suspicion of obstructive sleep-apnoea. and RDI (rho=0.28; P < 0.05) and HbSaO2 nocturnal nadir At the first scheduled visit, each patient completed an Italian (rho=−0.37; P < 0.001). version of the ESS, regardless of the presence and degree of The data show that the ESS distinguishes daytime sleepiness complaint of excessive daytime sleepiness at the clinical degree in OSAS patients, simple snorers, and healthy control interview. In each case a doctor sensitized the patient about subjects. It is likely that patient sensitization and prospective the issue of sleepiness before the scale completion, and remained use of the questionnaire improves the scale’s sensitivity. The available for any necessary clarification while the patient was correlation between the ESS score and some instrumental filling in the questionnaires. Within two weeks of completing markers of OSAS suggest that the ESS is a potentially useful the scale, each patient underwent a full night of laboratory or tool in the assessment of OSAS patients. ambulatory polysomnography. The study only considered those patients who received a REFERENCES definite diagnosis of obstructive sleep apnea (OSA) or simple snoring, in accordance with international criteria (Strohl and Douglass, A. B., Bornstein, R., Nino Murcia, G. et al. The Sleep Disorders Questionnaire I. Creation and Multivariate structure of Redlione 1996). Fifty-four subjects (45 males, 9 females, mean SDQ. Sleep, 1994, 17: 160–167. age 51.7, SD 9.8 years, mean Body Mass Index (BMI) 30.1, SD 5.9) received a definite diagnosis of OSAS. The mean Table 1 Correlation between ESS score and age, BMI, RDI, Respiratory Disorder Index (RDI) was 34.4, SD 22. TwentyHbSaO2 nadir: Spearman correlation six per cent of the patients had an RDI between 7 and 15; 24% between 16 and 30; 18% between 31 and 45; and the remaining RDI BMI Age (yr) HbSaO2 nadir 32% over 45. The mean nocturnal HbSaO2 nadir for the group BMI 0.087 of OSAS patients as a whole was 72.6% (SD 14). Age (yr) 0.16 0.09 Twenty patients (mean age 50.3, SD 11 years, 17 males, 3 HbSaO2 nadir −0.47∗∗∗ −0.35∗ −0.31∗ females; mean BMI 26.3, SD 3) were diagnosed as having ESS Tot 0.28∗ 0.30 0.09 −0.37∗∗ simple snoring (mean RDI 1.4, SD 1.6, mean nocturnal HbSaO2 nadir 94%, SD 1.5). ∗ P< 0.05, ∗∗ P< 0.01, ∗∗∗P< 0.001.