REM-related obstructive sleep apnoea in neuromuscular diseases: A 10-year retrospective cohort study

Neuromuscular diseases (NMDs) are reported to have increased obstructive apnoea/hypopnoea during rapid eye movement (REM) sleep; however, the prevalence of REM-related obstructive sleep apnoea (OSA) and its clinical correlates in NMD remain undefined. We evaluated REM sleep, REM-related OSA frequency, and associated with demographic and clinical factors.

We retrospectively evaluated patients with NMDs who underwent polysomnography (PSG) between 2015 and 2024. Demographic data, morning arterial blood gases, spirometry and PSG data were collected. REM-related OSA required AHI ≥ 5 events/hour, REM-to-non-REM (NREM) AHI ≥ 2, and REM ≥ 30 min; REM-isolated additionally required NREM AHI < 5 events/hour. Patients with OSA who did not meet the criteria for REM-related OSA were classified as having NREM-related OSA.

Among 290 patients, OSA was present in 87.6% (254/290). REM sleep duration was markedly reduced (11.8 ± 8.0%; 46.8 ± 32.2 min), and 30.0% of patients had REM duration < 30 min. Among OSA with REM ≥ 30 min (n = 182), 54.4% had REM-related OSA; 25.3% were REM-isolated. Compared with NREM-related OSA, the REM-related group exhibited more frequent female sex (p = 0.015), hypertension (p = 0.020), and depression (p = 0.025). In multivariable analysis, REM-related OSA was independently associated with morning hypercapnia (aOR 4.889; 95%CI 1.885-12.680), forced vital capacity (FVC) < 50% and/or ≥ 20% upright-to-supine decline (aOR 3.847; 95%CI 1.085-13.642), and mild OSA (aOR 3.461; 95%CI 1.509-7.937).

Despite the marked reduction in REM sleep in NMDs, OSA, and particularly REM-related OSA, is common. In the REM-related OSA group, morning hypercapnia and FVC decline were more frequent. These observations suggest that REM-stage characteristics may be predictive of subsequent chronic respiratory failure.