Objectives To investigate the prevalence of positional obstructive sleep apnea (P-OSA) and rapid eye movement-related OSA (REM-OSA) in children with OSA and identify related factors. 

This was a cross-sectional study among children aged 2–12 years diagnosed with OSA using overnight polysomnography (PSG) between August 1, 2020 and July 31, 2021. Demographics, anthropometrics, PSG, and OSA-18 questionnaire data were recorded.

Data from a total of 474 children were available for analysis. Children had a median age 4.8 (4.1, 6.4) years, 66.7% were male, and 23.2% were obese. The prevalence of P-OSA was 38.2% and that of REM-OSA was 43.0%. P-OSA was correlated with age and OAHI (odds ratio [OR]=1.172, 0.947; P=0.005, <0.001, respectively), but not sex, obesity, and adenoid and tonsil size (OR=1.265, 0.785, 0.826, 0.989; P=0.258, 0.327, 0.153, 0.905, respectively). REM-OSA was correlated with age, adenoid size, tonsil size, and OAHI (OR=0.876, 1.320, 1.387, 1.021; P=0.024, 0.040, 0.001, 0.042) but not with sex and obesity (OR=0.910, 1.281; P=0.643, 0.315). 

The prevalence of P-OSA was 38.2% and that of REM–OSA was 43.0% in children with OSA. Age was correlated with both the prevalence of P-OSA and REM-OSA, with an increasing and decreasing prevalence as children grew older, respectively. The severity of OSA was significantly associated with the prevalence of both P-OSA and REM-OSA. Adenoid and tonsil size were correlated with the prevalence of REM-OSA but not P-OSA. Obesity and sex were not associated with the prevalence of P-OSA or REM-OSA.