REM-associated obstructive sleep apnoea in interstitial lung disease associates with more severe disease

<bold>Background:</bold> Rapid-eye movement (REM) sleep is associated with increased upper airway collapsibility, decreased respiratory drive and increased sympathetic tone, causing increased frequency and severity of obstructive sleep apnoea (OSA). Interstitial lung disease (ILD) may predispose to OSA but data is limited as to prevalence and significance of REM-OSA in ILD. <bold>Methods:</bold> Observational study of 102 patients with ILD who had home sleep studies and one-year follow up. REM-predominant OSA (REM-OSA) is defined as AHI ≥ 5, REM AHI/NREM AHI ≥ 2, NREM-AHI ≤ 8 and REM sleep time ≥ 30 minutes. Non-REM predominant OSA (NREM-OSA) required AHI ≥ 5, but not fulfilling the other criteria, and patients with an AHI<5 had no OSA. Groups were compared using one-way ANOVA, post-hoc Tukey’s test and Kaplan-Meier survival analysis. <bold>Results:</bold>REM-OSA was observed in 12/102 (11.8%); NREM-OSA in 60/102 (58.8%) and no OSA in 30/102 (29.4%). Mean difference in AHI between REM and NREM sleep was 7.9 ± 10.8. Patients with REM-OSA had higher mean BMI (31.4±10.8kg/m2; p=0.02) but less severe OSA than patients with NREM-OSA (AHI 9.7±4.7events/hr vs 19.9±9.4; p<0.001). Patients with REM OSA had more severe impairment of lung function (Figure 1), but there was no difference in progression-free survival between the groups (p=0.87). <fig><object-id>erj;64/suppl_68/PA1562/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Interpretation:</bold> REM-OSA was associated with higher BMI and more severe ILD, but less severe OSA.