# REM‐OSA vs NREM‐OSA in Children: Separate Clinical Phenotypes or Markers of OSA Severity

## TL;DR

This study examines whether REM-OSA and NREM-OSA in children are distinct types of sleep apnea or just indicators of disease severity.

## Contribution

The study provides evidence that REM-OSA and NREM-OSA are severity markers rather than separate clinical phenotypes in pediatric OSA.

## Key findings

- REM-OSA and NREM-OSA groups did not differ in gender, BMI, diagnosis, symptoms, or oxygenation indices.
- The REM-OSA group had lower OAHI and less severe OSA compared to the NREM-OSA group.
- Low OAHI was the only significant predictor of REM-OSA and higher REM-AHI/NREM-AHI ratio.

## Abstract

Obstructive sleep apnea (OSA) occurs predominantly during REM sleep (REM‐OSA) compared to NREM sleep (NREM‐OSA) in both children and adults. However, it is not clear whether REM‐OSA and NREM‐OSA are separate clinical phenotypes of OSA or represent 2 ends of OSA severity spectrum.

We aimed to compare clinical and polysomnography (PSG) characteristics of REM‐OSA versus NREM‐OSA in children, and to evaluate the effect of these characteristics on REM‐related over NREM‐related obstructive AHI ratio (REM‐OAHI/NREM‐OAHI).

Clinical and PSG data of all children diagnosed with moderate to severe OSA by PSG between 2019 and 2024 were collected and analyzed. REM‐OSA was defined as REM‐OAHI/NREM‐OAHI ratio of ≥2. NREM‐OSA was defined as REM‐OAHI/NREM‐OAHI of < 2.

A total of 253 patients (169 male and 84 female) met the inclusion criteria. REM‐OSA was identified in 174 (68.7%) patients, and NREM‐OSA in 79 (31.2%) patients. There was no significant difference between REM‐OSA and NREM OSA groups in gender, BMI, clinical diagnosis, symptoms or oxygenation indices. However, REM‐OSA group had lower OAHI and less severe OSA than NREM‐OSA group (p = 0.004, p = 0.003, respectively). Regression analysis showed that low OAHI was the only significant predictor of REM‐OSA and the only predictor of high REM‐AHI/NREM‐AHI ratio, respectively (p = 0.001, p = 0.001).

REM‐OSA and NREM‐OSA are not likely to be separate clinical phenotypes of OSA but only markers of the disease severity, with NREM‐OSA indicating more severe disease.