Obstructive Sleep Apnea Non-PAP Outcomes and Viable Alternatives

OSANOVA is a non-randomized clinical trial which aims to compare outcomes of mandibular advancement device (MAD) and hypoglossal nerve stimulation (HGNS) therapies in moderate-to-severe OSA patients who fail, decline, or are intolerant to positive airway pressure (PAP) therapy (referred to as PAP-failing patients). The primary aim of the study is to compare the outcomes between PAP-failing moderate-to-severe OSA patients receiving MAD and those receiving HGNS therapy. Primary Outcome measures include changes in Pittsburgh Sleep Quality Index (PSQI) scores. Secondary aims will help us describe the outcomes between PAP-failing moderate-to-severe OSA patients receiving MAD and those receiving HGNS therapy. Secondary outcome measures include: * adverse events, * Epworth Sleepiness Scale (ESS), * Symptoms of Nocturnal Obstruction and Related Events (SNORE-25), * patient-reported satisfaction, * CGI-Improvement, * the rate of subjects re-selecting the treatment, and * the rate of subjects recommending the treatment. and * changes in sleep study metrics (i.e., AHI, ODI, mean arterial saturation, and Time\<90%),