Low Arousal Threshold and Long-Term Adherence to Hypoglossal Nerve Stimulation.

IMPORTANCE: A low arousal threshold (ArTH) is a common pathophysiologic endotype in obstructive sleep apnea (OSA) and has been associated with poor sleep quality and reduced adherence to positive airway pressure therapy. Its impact on adherence to hypoglossal nerve stimulation (HGNS) is unclear. OBJECTIVE: To evaluate the association between baseline ArTH and HGNS adherence and outcomes. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study took place at 2 academic medical centers (University of Pittsburgh Medical Center and Thomas Jefferson University Hospital). Participants included adults who underwent HGNS implantation between January 2021 and December 2023, with preoperative sleep study data sufficient to calculate ArTH and objective device adherence data available at the 3- and 6-month follow-up. EXPOSURE: Preoperative ArTH status (low vs high), estimated using a validated composite scoring algorithm based on apnea-hypopnea index (AHI), oxygen desaturation nadir, and hypopnea proportion from routine sleep study data. MAIN OUTCOMES AND MEASURES: The primary outcome was categorical HGNS adherence (≥4 h/night on >70% of nights over a 90-day period) at 3 and 6 months postactivation. Secondary outcomes included continuous adherence metrics (h/night, percentage of nights used, percentage of nights with ≥4 hours of use, pauses per night) and longitudinal adherence transition patterns between time points. RESULTS: Among 160 included patients (median [IQR] age, 66.1 [58.9-72.1] years; 105 [66%] male), 65 (41%) had low ArTH and 95 (59%) had high ArTH. Patients with high ArTH, compared with those with low ArTH, had higher baseline AHI (median [IQR], 39.0 [30.7-47.1] events/h vs 20.8 [17.3-25.8] events/h) and greater relative reduction in AHI after HGNS (median [IQR], -53.7% [-67.8% to -6.4%] vs -33.8% [-67.8% to -5.4%]). Low ArTH was associated with transition from adherence at 3 months to nonadherence at 6 months (17 of 65 patients [26%] vs 5 of 95 patients [5.3%]; odds ratio, 12.60; 95% CI, 3.70-56.10). Average nightly use duration and pauses/night did not differ meaningfully between groups. CONCLUSIONS AND RELEVANCE: This cohort study demonstrates that low ArTH is associated with progressive disengagement from HGNS therapy, characterized by missed nights of therapy rather than nightly use intolerance. Incorporating ArTH endotyping into preoperative evaluation may identify patients at risk for therapy disengagement, enabling personalized counseling and guided strategies to improve HGNS adherence and patient outcomes.