Figure 2.

Relationship among a low arousal threshold (ArTH), the sleep duration at baseline, and the longitudinal continuous positive airway pressure (CPAP) adherence. A directed acyclic graph and mediation analysis model for the change in CPAP adherence caused by a change in the ArTH (see also Table 2) as mediated by the total sleep time at baseline (P = 0.010 for mediation) is shown. A lower total sleep time at baseline accounted for 23.5% (interquartile range, 2.3–100.0%) of the relationship between the ArTH and CPAP adherence (12 min of the 49-min decrease in CPAP use were attributed to each 1-SD decrease in the ArTH).