Predictive factors and screening strategy for obstructive sleep apnea in patients with advanced multiple sclerosis

Background: Obstructive sleep apnea (OSA) screening questionnaires have been evaluated in Multiple Sclerosis (MS) but not yet validated in patients with advanced disease. The aim of this study is to identify OSA predictive factors in advanced MS and to discuss screening strategies. Methods: Oximetry data from 125 patients were retrospectively derived from polysomnographic reports. Univariate and multivariate analysis were used to determine predictive factors for OSA. A two -level screening model was assessed combining the oxygen desaturation index (ODI) and a method of visual analysis. Results: multivariate analysis showed that among the clinical factors only age and snoring were associated with OSA. Usual predictive factors such as sleepiness, Body mass index (BMI) or sex were not significantly associated with increased Apnea Hypopnea Index (AHI). The ODI was highly predictive ( p < 0.0001) and correctly identified 84.1 % of patients with moderate OSA and 93.8 % with severe OSA. The visual analysis model combined with the ODI did not outperform the properties of ODI used alone. Conclusion: As the usual clinical predictors are not associated with OSA in patients with advanced MS, questionnaires developed for the general population are not appropriate in these patients. Nocturnal oximetry seems a pertinent, ambulatory and accessible method for OSA screening in this population.