Relation between arousability and outcome of upper airway stimulation in the Stimulation for Apnea Reduction (STAR) Trial.

Study Objectives: Upper airway stimulation (UAS) is an innovative surgical treatment for obstructive sleep apnea; however, the treatment failure rate is approximately 22%. Easy arousability may limit the tolerability of stimulation and, by extension, its effectiveness. The odds ratio product (ORP) is a continuous electroencephalographic metric of arousal propensity (range: 0 [deep sleep] to 2.5 [full wakefulness]), and its rate of decline after arousal (ORP-9) is a risk factor for susceptibility to arousal in the presence of frequent arousal stimuli. We hypothesized that individuals with deeper sleep (low average ORP and low ORP-9) are more likely to respond to UAS.

Methods: ORP and ORP-9 were calculated from 126 baseline polysomnograms of participants in the STAR Trial. These values were compared between responders and nonresponders. Adjusted linear modeling was performed to determine the association between ORP-derived variables and treatment response.

Results: No differences were found between responders and nonresponders in unadjusted comparisons of ORP-derived variables. On linear regression modeling, significant correlation was found between non-rapid eye movement ORP and reduction in apnea-hypopnea index (P = .004).

Conclusions: No significant difference in ORP was noted between responders and nonresponders to UAS therapy; however, contrary to our initial hypothesis, linear regression modeling trended toward a positive relationship between ORP and UAS response, suggesting that those who have lighter sleep are more likely to respond to therapy; however, these results are only exploratory, and future larger prospective studies are needed to confirm this relationship.

Clinical Trial Registration: Registry: ClinicalTrials.gov; Name: STAR Trial; Identifier: NCT01161420.