Stepwise Add-On and Endotype-informed Targeted Combination Therapy to Treat Obstructive Sleep Apnea: A Proof-of-Concept Study.

Rationale: Oral appliance therapy (OAT) is an effective treatment for many people with obstructive sleep apnea (OSA). However, OSA pathogenesis is heterogeneous, and, in ∼50% of cases, OAT does not fully control OSA. Objectives: This study aimed to control OSA in individuals with an incomplete response to OAT alone by using additional targeted therapies informed by OSA endotype characterization. Methods: Twenty-three people with OSA (apnea-hypopnea index [AHI], 41 ± 19 events/h) not fully resolved (AHI, >10 events/h) with OAT alone were prospectively recruited. OSA endotypes were characterized pretherapy during a detailed physiology study night. Initially, an expiratory positive airway pressure (EPAP) valve and supine avoidance device therapy were added to target the impaired anatomical endotype. Those with residual OSA (AHI, >10 events/h) then received one or more nonanatomical interventions based on endotype characterization. This included O₂ (4 L/min) to reduce high loop gain (unstable respiratory control) and 80/5 mg atomoxetine-oxybutynin to increase pharyngeal muscle activity. Finally, if required, OAT was combined with EPAP and continuous positive airway pressure (CPAP) therapy. Results: Twenty participants completed the study. OSA was successfully controlled (AHI, <10 events/h) with combination therapy in all but one participant (17 of 20 without CPAP). OAT plus EPAP and supine avoidance therapy treated OSA in 10 (50%) participants. OSA was controlled in five (25%) participants with the addition of O₂ therapy, one with atomoxetine-oxybutynin, and one required O₂ plus atomoxetine-oxybutynin. Two participants required CPAP for their OSA, and another was CPAP intolerant. Conclusions: These novel prospective findings highlight the potential of precision medicine to inform targeted combination therapy to treat OSA. Clinical trial registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618001995268).