Abstract Introduction Studies examining long-term outcomes of hypoglossal nerve stimulation (HNS) by positional phenotype remain limited. This study evaluated 1-year HNS outcomes in patients with positional obstructive sleep apnea (POSA) and non-POSA, and additionally assessing post-treatment changes in positional phenotype. Methods We retrospectively reviewed adults who underwent HNS at a tertiary sleep center between December 2020 and January 2024. To ensure reliable positional indices, only patients who slept ≥15 minutes in both supine and non-supine positions were analyzed. POSA defined as a supine AHI more than twice the non-supine AHI. Thirty-eight patients (POSA=20, non-POSA=18) who completed baseline and 1-year follow-up sleep apnea testing were analyzed. Outcomes included total AHI, supine AHI, non-supine AHI, minimum oxygen saturation (MinSpO₂), and Epworth Sleepiness Scale (ESS) scores. Results In the overall cohort, median total AHI improved from 32.6 to 11.1/h (p 0.001). Supine AHI decreased from 43.3 to 17.1 (p 0.001) and non-supine AHI from 16.7 to 7.0 (p=0.001). ESS scores improved from 8.0 to 6.0 (p=0.003). When comparing phenotypes, total and supine AHI reductions were similar between POSA and non-POSA. However, non-supine AHI improved markedly in non-POSA compared to POSA (30.3 vs 0.9; p 0.001), with a greater percent reduction (73.0% vs 27.9%; p=0.025). Within non-POSA group, non-supine AHI reduction was also greater than supine AHI reduction (30.3 vs 18.4, p 0.001). Regarding phenotype stability, 65% of baseline POSA and 50% of baseline non-POSA maintained the same position-dependency after 1 year. Patients who remained non-positional (n=9) showed no significant total AHI improvement (p=0.086) and had persistently elevated AHI (30.6/h). In contrast, baseline POSA improved significantly regardless of position-dependency change, and non-POSA patients who became position-dependent also exhibited significant reductions in total AHI. Conclusion Long-term HNS significantly improved respiratory and clinical outcomes in both phenotypes. While total and supine AHI responses were comparable, non-supine AHI improved predominantly in non-POSA patients than POSA. In non-POSA, respiratory events in non-supine position improved more than in supine position. Persistent non-position dependency after treatment was associated with suboptimal outcomes, suggesting that such patients may benefit from earlier adjunctive or combination therapies. Support (if any)
Han et al. (2026) studied this question.