Tongue function and high-risk sleep-disordered breathing in youth: age-stratified associations and interactions in a Vietnamese cross-sectional study

To examine associations between tongue function domains and questionnaire-based high-risk sleep-disordered breathing classification across age groups, and to explore interaction effects between functional and anatomical factors. A cross-sectional study included 1,244 participants (462 children aged 6–8 years and 782 young adults aged 18–25 years). High-risk classification was defined as meeting ≥ 1 age-appropriate threshold: Pediatric Sleep Questionnaire (PSQ ≥ 8), Epworth Sleepiness Scale (ESS > 10), or Snoring Severity Scale (SSS ≥ 7) for children; Berlin Questionnaire (≥ 2 positive categories), ESS > 10, or SSS ≥ 7 for young adults. Tongue function included mobility, strength, posture, and orofacial domains. Multivariable logistic regression with backward stepwise selection was used in pooled and age-stratified models. Pre-specified interaction terms were systematically tested to explore effect modification between functional and anatomical factors. The prevalance of high-risk classification was 26.8% in children, 11.9% in young adults, and 17.5% overall. In children, low tongue resting posture (AOR = 1.69) and frequent nocturnal open-mouth posture (AOR = 2.69) were independently associated with high-risk classification. In young adults, better orofacial function (AOR = 0.79), greater posterior mobility (AOR = 0.96), and higher posterior strength (AOR = 0.98) were protective. Posterior mobility and age group moderated the association between tonsillar hypertrophy and high-risk classification (AOR = 0.53 and AOR = 2.06, respectively), though not in age-stratified models. In children, combined tonsillar hypertrophy and restricted posterior mobility were associated with substantially higher prevalence (34.5% vs. 13.8%; dose-response p=.006). Tongue function showed age-group-specific associations with questionnaire-based high-risk classification. Incorporating both anatomical and functional assessments within age-specific frameworks may improve early identification and inform future research.