Applicability of the Epworth Sleepiness Scale to fibromyalgic women with sleep apnea–hypopnea syndrome

Introduction Sleep apnea–hypopnea syndrome (SAHS) and fibromyalgia (FM) are two diseases of unknown etiology that share a distinctive feature: the great importance of subjective symptoms when it comes to establishing their seriousness. Even though they are prevalent entities in Spain, as in the rest of Western civilization, there are few cases described in which these syndromes concur; likewise, differentiating elements which can influence in diagnosis and therapeutic management have not been established. Tools used in the study of SAHS are frequently used even though they have not been completely validated for all groups of patients, especially for the female population. This happens when applying the Epworth Sleepiness Scale (ESS), used to measure pathological daytime hypersomnia. Materials and methods For this analysis we have featured 11 incidental cases of women diagnosed with FM among all the 2824 patients that were diagnosed with SAHS by the Pneumology Service of the Hospital General Universitario de Alicante (HGUA) between the dates of January 1998 and December 2008 by polysomnographic or polygraphic study. It has been researched the relationship between self-referred somnolescence and the scores obtained via the ESS. Both sets of data were complimented and were registered according to the protocol used when facing any case of suspected SAHS at the HGUA. For statistical treatment, the ESS has been stratified into two levels: from 12 to 24 points and less than 12 points – in keeping with the limit established between pathological hypersomnia and non-pathological somnolence. Results The validity values of the ESS have been calculated in base to a receiver operating characteristic (ROC) curve analysis: area under the curve (AUC) of 0.70 (p-value > 0.005, asymptotic 95% confidence interval [lower bound: 0, upper bound: 1]) with 40% sensitivity and 100% specificity. Conclusion In conlusion, there is not enough evidence to state that the Epworth Questionnaire is useful for establishing the presence of daytime somnolence in this group of fibromyalgic women with sleep apnea–hypopnea syndrome, but it could be more utile for controlling the evolution of patients under treatment. However, this tendency would need to be confirmed by wider range studies.