Clinical factors predicting the severity of obstructive sleep apnea in interstitial lung disease

Background and Objectives: Obstructive sleep apnea (OSA) is known to be one of the common complications of interstitial lung disease (ILD). Although it is suspected that the incidence of OSA and the progression of ILD are closely related to each other, the clinical features of ILD with such complications are not fully understood. The aim of this study is to clarify specific clinical factors in ILD patients that predict the complication and the severity of OSA.Study Design and Method: ILD patients in our institute were prospectively investigated for the incidence of OSA by polysomnography (PSG).Results: All 33 patients were diagnosed with OSA. Univariate regression analysis showed a lower Diffusing capacity of the lung for carbon monoxide (DLco) and a lower respiratory rate (RR) predicted a higher HI and a higher AI, respectively. Multivariate regression analysis showed a lower DLco and a lower RR also predicted a higher apnea hypopnea index (AHI).Conclusions: A high prevalence of OSA was exhibited in our study of ILD patients. Lacking rapid breathing pattern and impaired diffusing capacity were predictive factors for the severity of OSA. The examination of sleep disorders should be actively considered for these patients.Short title: The relationship between ILD and OSA