Comparisons of the therapy effects on upper airway dimensions
low respiratory arousal, OSA, airway narrowing
SECONDARY, PATHOGENESIS
The changes of CSAmin induced by MAD were not significantly different between responders and non-responders in the present study. Besides the CSAmin, the secondary outcome variables, including the lateral dimensions and the anteroposterior dimensions of the CSAmin, upper airway volume, and upper airway length, were not significantly different between both groups either. Contrary to our results, Chan et al. [In the present study, the observed effect size f of the difference in the changes of CSAmin between both groups (0.37 and 0.25 in the primary and sensitivity analyses, respectively) was between medium and large (according to Cohen [Our results suggest that the effects of MAD on upper airway dimensions are similar between responders and non-responders in the supine position, although the changes of AHI and AHI-supine differed significantly. The non-significant findings of comparisons of upper airway dimensions do not support our initial hypothesis. However, the multifactorial nature of the pathogenesis of OSA may possibly explain our findings. It has been recognized that besides anatomical factors, non-anatomical factors like impaired pharyngeal dilator muscle responsiveness, increased propensity for awakening during airway narrowing (low respiratory arousal threshold), and respiratory control instability (high loop gain) are also crucial determinants of OSA for many patients [