Systemic exertion intolerance disease/chronic fatigue syndrome is common in sleep centre patients with hypersomnolence: A retrospective pilot study.

Symptoms of the central disorders of hypersomnolence extend beyond excessive daytime sleepiness to include non-restorative sleep, fatigue and cognitive dysfunction. They share much in common with myalgic encephalomyelitis/chronic fatigue syndrome, recently renamed systemic exertion intolerance disease, whose additional features include post-exertional malaise and orthostatic intolerance. We sought to determine the frequency and correlates of systemic exertion intolerance disease in a hypersomnolent population. One-hundred and eighty-seven hypersomnolent patients completed questionnaires regarding sleepiness and fatigue; questionnaires and clinical records were used to assess for systemic exertion intolerance disease. Sleep studies, hypocretin and cataplexy were additionally used to assign diagnoses of hypersomnolence disorders or sleep apnea. Included diagnoses were idiopathic hypersomnia (n = 63), narcolepsy type 2 (n = 25), persistent sleepiness after obstructive sleep apnea treatment (n = 25), short habitual sleep duration (n = 41), and sleepiness with normal sleep study (n = 33). Twenty-one percent met systemic exertion intolerance disease criteria, and the frequency of systemic exertion intolerance disease was not different across sleep diagnoses (p = .37). Patients with systemic exertion intolerance disease were no different from those without this diagnosis by gender, age, Epworth Sleepiness Scale, depressive symptoms, or sleep study parameters. The whole cohort reported substantial fatigue on questionnaires, but the systemic exertion intolerance disease group exhibited more profound fatigue and was less likely to respond to traditional wake-promoting agents (88.6% versus 67.7%, p = .01). Systemic exertion intolerance disease appears to be a common co-morbidity in patients with hypersomnolence, which is not specific to hypersomnolence subtype but may portend a poorer prognosis for treatment response.

Validation of the self-administered version of the international Restless Legs Syndrome study group severity rating scale - The sIRLS.

INTRODUCTION: The International Restless Legs Study Group (IRLSSG) has developed the IRLS (International Restless Legs Syndrome Severity Scale) and validated it as a clinician/researcher administered scale to be used when both patient and examiner are present. The IRLSSG recognized the need for a self-completing scale that can be used economically in clinical practice and in large population-based studies. In this study the validity and the reliability of the IRLS as a self-administered scale (sIRLS) is assessed. METHODS: Established RLS patients were recruited by eight centers in four countries and consented to participate in this study. The validity of the sIRLS was assessed by patients completing the sIRLS before a clinician administered the IRLS. The reliability of the sIRLS was assessed by patients completing the sIRLS again, two weeks after the first one, provided no change had occurred. RESULTS: Overall, 173 patients were recruited and 164 of them were included in the analyses. The sIRLS showed satisfactory scaling assumptions and no relevant floor or ceiling effect. One factor explained 61.3% of the variance. Cronbach's alpha was 0.93 and the item homogeneity index was 0.59. Intraclass correlation coefficient between the sIRLS and the IRLS was 0.94. The sIRLS standard error of measurement was 3.61 (½ SD at baseline = 4.11). The results mostly overlapped those of the IRLS analyzed in parallel. DISCUSSION: The sIRLS is a reliable, valid and precise instrument that showed tight association with the IRLS. These findings support the use of the sIRLS for self-evaluation of RLS severity. The responses obtained on the sIRLS and the IRLS scale varied slightly. Therefore, we recommend that either the sIRLS or the IRLS scale be used as the only scale for serial measures over time.