REM obstructive sleep apnea: prevalence and clinical associations in a high-altitude population.

Study objectives: REM-associated OSA (REM OSA) has a prevalence of 17-74% of all OSA cases. At high altitude and in Latin America, there are no data on REM OSA and its relationship to daytime sleepiness and comorbidities. This study aimed to determine the prevalence of REM OSA and the differences in clinical and polysomnographic characteristics between OSA and REM OSA in a population living at 2640 m.

Methods: A retrospective cross-sectional study was conducted on adults in Bogotá, Colombia between January and December 2022. Patients were considered to have REM- OSA if they had a REM sleep duration of at least 30 minutes and the ratio of REM-AHI to NREM-AHI was > 2, and NREM-AHI < 15. For comparing the OSA and OSA REM groups, the X² or Fisher's exact test was used for the qualitative variables and Student's t-test or its non-parametric counterpart for the quantitative variables.

Results: Patients with REM OSA and mild OSA had more severe nocturnal desaturation indices compared to mild NREM OSA. Patients with OSA had a higher prevalence of arterial hypertension and ischemic heart disease.

Conclusions: REM OSA prevalence in a population living at high altitude was low compared with other studies. The patients with REM OSA and mild OSA had more severe nocturnal desaturation indexes compared to REM OSA at sea level. This study suggests a possible subgroup of patients with mild OSA at high altitude who may benefit from a discussion about initiating CPAP therapy.