The multisystem burden of REM related obstructive sleep apnoea: evidence from a clinical cohort

REM-related OSA, with events mainly in REM sleep, is increasingly recognised as a distinct phenotype. Its relationship with systemic comorbidities remains unclear. This study aimed to evaluate the prevalence of cardio-metabolic, respiratory and psychiatric comorbidities in REM- versus non-REM-related OSA. Subjects undergoing polysomnography were included, excluding those with incomplete data, sleep efficiency < 60%, no OSA or other sleep disorders, REM sleep < 30 min, uncontrolled malignancy, prior upper airway surgery, severe lung disease, sedative use, or ongoing positive airway pressure/oral appliance therapy. Demographics, comorbidities, Epworth Sleepiness Scale (ESS) and polysomnographic data were recorded. A total of 2240 OSA patients were analysed (1541M/699F; mean age 49.9 ± 11.6 years; BMI 31.6 ± 5.7 kg/m²): 32.6% mild, 31.1% moderate, 36.3% severe. REM-related OSA was identified in 18.3%. It showed lower apnoea-hypopnoea index and oxygen desaturation index, the percentage of sleep time with SpO₂ < 90% but higher mean and nadir nocturnal oxygen saturation (all p < 0.001). REM-related OSA patients were younger, more often female (p = 0.002, p < 0.001) and had more comorbidities. In multivariable logistic regression adjusting for age, sex, ESS, OSA severity, and comorbidities, REM-related OSA was independently associated with hypertension, coronary artery disease, hypothyroidism, and asthma (p = 0.001, p = 0.003, p < 0.001, p < 0.001 respectively). REM-related OSA is a distinct clinical entity marked by a higher prevalence of comorbidities despite lower standard measures of disease severity. Clinicians should consider alternative screening and lower treatment thresholds for high-risk groups, including young women and those with comorbidities.