Pathological Endotypic Traits of Paediatric Obstructive Sleep Apnea: Age and Sex Differences

ABSTRACT Background and Objective Paediatric obstructive sleep apnea (OSA) has a distinct pathophysiology and management from that of adults, yet endotypic traits in this population remain underreported. Understanding how these traits vary by age and sex could provide insights into respiratory system development. This study aims to examine the association of age and sex with endotypic traits in children and adolescents with OSA. Methods Between April 2020 and September 2024, we prospectively enrolled 88 patients aged ≤ 18 years who were referred to a single clinical sleep center in Taiwan for in‐laboratory diagnostic polysomnography. Patients with an apnea‐hypopnea index (AHI) ≥ 1 h −1 were included. Endotypic traits were estimated using polysomnographic signals. Linear regression analysis was performed to assess the associations of endotypic traits with AHI, age, and sex. Results Poor compensation, worse collapsibility, and high loop gain were associated with higher AHI, with compensation explaining the largest variance (12.85%) among all endotypic traits. Patients older than 12 years exhibited a more compromised upper airway ( V min : 64.3 vs. 71.4% eupnea) and higher loop gain (LG 1 : 0.45 vs. 0.34) than younger patients, independent of AHI. No significant sex differences in endotypic traits were observed. Conclusions In addition to upper airway collapsibility, inadequate compensatory activity of the dilator muscles significantly contributed to higher AHI in paediatric patients with OSA. The age‐related decrease in upper airway patency may result from the interplay between upper airway and craniofacial development.