Skip to main content
. 2019 Nov;16(11):1422–1431. doi: 10.1513/AnnalsATS.201903-190OC

Table 2.

Traits associated with oral appliance efficacy: multiple regression

Variable β-Value SEM β-SD P Value Interpretation
Constant 47.1 5.1 1.4 <0.0001  
Pharyngeal traits          
 VPASSIVE −0.771 0.325 −0.47 0.02 Not severe and not mild collapsibility → success
 VPASSIVE2 −0.0293 0.0095 −1.1 0.003
 Compensation2 0.0215 0.0067 0.94 0.002 Higher compensation → failure
 Compensation × arousal threshold 0.0486 0.0107 1.4 <0.0001 Particularly when arousal threshold is low or response to arousal is high
 Compensation × response to arousal −0.0171 0.0064 −0.41 0.009  
Nonpharyngeal traits          
 Loop gain −112 41 −0.37 0.008 Higher loop gain → failure
 Loop gain × compensation −6.95 2.23 −0.52 0.003 Particularly when compensation or response to arousal is high
 Loop gain × response to arousal −8.79 2.52 −0.70 0.0008  
Arousal threshold 0.420 0.233 0.32 0.076 Lower arousal threshold → failure
Arousal threshold2 0.0151 0.0055 0.51 0.007
Response to arousal −0.514 0.193 −0.34 0.009 Higher response to arousal → failure
Response to arousal × VPASSIVE −0.0212 0.0115 −0.50 0.069

Definition of abbreviations: SD = standard deviation; SEM = standard error of the mean; VPASSIVE = passive collapsibility.

Oral appliance efficacy is defined as the percentage reduction in apnea–hypopnea index with treatment compared with baseline (transformed; see Methods). The table describes final results (12 of 20 terms) after backward stepwise elimination (P-to-remove = 0.157), which began with five traits, their squares, and all interaction terms. Note that the significance levels were P < 0.05 in 10 of 20 terms and P < 0.01 in 9 of 20 terms. Traits were mean subtracted before terms were generated and applied to the model (see below). β-SD describes the number of SDs of change in treatment efficacy per SD increase in each term (1.3 SD is needed to move a typical nonresponder to a typical responder). Mean values of the endotypic traits before mean substraction: VPASSIVE = 79.0 ± 20.8; loop gain = 0.43 ± 0.11; compensation = −9.5 ± 27.0%; arousal threshold = 141.8 ± 26.0%; response to arousal = 36.3 ± 22.6%. A regression model cutoff of 60% (predicted reduction in apnea–hypopnea index, untransformed) was used to define predicted responders and predicted nonresponders (maximized sensitivity plus specificity). Overall R2 = 0.30; adjusted R2 = 0.19; P = 0.003.