Linking phenotype with obstructive sleep apnoea severity: A cross-sectional cephalometric and polysomnographic study of obstructive sleep apnoea patients

Abstract

Background Cephalometric features have been identified as phenotypic traits of individuals with obstructive sleep apnoea (OSA). However, few studies have investigated how cephalometric parameters varied with OSA severity, especially in the Asian population. Objectives The aim of this study was to investigate the relationship between cephalometric parameters and severity of OSA in the Southeast Asian Chinese population. A novel cephalometric measurement, length of soft palate below the functional occlusal plane, was also studied. Methods In this retrospective cross-sectional study of 113 Southeast Asian Chinese patients with OSA diagnosed by overnight polysomnography, the association of cephalometric parameters with the apnoea-hypopnoea index (AHI) was evaluated, controlling for age, gender and body mass index (BMI). STROBE guidelines were used in this study. Results Positive association was found between age and AHI (Median Regression Coefficient = 0.26; 95% CI 0.07 to 0.44; p = 0.006). The distance of hyoid bone to mandibular plane was positively associated with AHI (Median Regression Coefficient = 0.58; 95% CI 0.05 to 1.11; p = 0.032), but the correlation did not reach statistical significance after Bonferroni correction ( p = 0.64) or adjustment for age, gender and BMI ( p = 0.106). Median regression analyses revealed a statistically significant negative correlation between facial axis angle and AHI (Median Regression Coefficient = −0.53; 95% CI - 1.04 to −0.01; p = 0.046), after adjusting for age, gender and BMI. Conclusion This study indicated that AHI was positively associated with age and negatively associated with facial axis angle.