Abstract
BACKGROUND: Hypoglossal nerve stimulation (HGNS) is an established surgical therapy for obstructive sleep apnea (OSA), yet treatment response is variable and appears to be influenced by both body mass index (BMI) and pattern of upper airway collapse. Whether excess body weight differentially affects HGNS efficacy across pharyngeal collapse patterns remains unclear. METHODS: We combined data from two independent HGNS cohorts (n=760) to examine whether the association between BMI and HGNS efficacy depends on pharyngeal collapse pattern identified by drug-induced sleep endoscopy. Collapse was categorized as predominantly laterally directed or anteroposterior (AP). Multivariable regression models assessed HGNS efficacy-quantified primarily as percent reduction in apnea-hypopnea index (AHI) on titration polysomnography and secondarily as treatment success (≥50% AHI reduction to <15 events/h)-while testing for effect modification by collapse pattern and adjusting for baseline AHI, partial collapse, surgical center, follow-up sleep study type, and prior or concomitant pharyngeal surgery. RESULTS: Increasing BMI was associated with substantially lower HGNS efficacy among patients with laterally directed collapse, whereas the relationship between BMI and efficacy was attenuated in those with AP collapse. Specifically, each 5 kg/m(2) increase in BMI was associated with a -19.7% (95% CI: -33.2 to -6.2) greater reduction in efficacy in lateral collapse compared with -3.8% (-8.0 to 0.36) in AP collapse (interaction p=0.027). Higher BMI also corresponded to reduced odds of treatment success in lateral collapse (odds ratio 4.4 [95% CI: 1.4-14.3] per 5 kg/m(2)), with no significant association observed in AP collapse (1.1 [0.75-1.5]; interaction p=0.023). CONCLUSIONS: The influence of BMI on HGNS treatment response differs meaningfully by pharyngeal collapse phenotype. Incorporating collapse pattern into BMI-based eligibility criteria may improve patient selection and optimize HGNS outcomes.