How we measure hypoglossal nerve stimulator outcome matters: titration versus single amplitude efficacy sleep studies.

Abstract

Study objectives: Hypoglossal nerve stimulation (HGNS) is a common treatment for obstructive sleep apnea (OSA). Objective assessment of HGNS efficacy measures apnea-hypopnea index (AHI) by multi-amplitude titration polysomnography (tPSG) and/or a single amplitude efficacy sleep study (eHST). Both tests have been used to determine efficacy despite significantly different protocols. This project's aim was to determine differences in objective outcomes in HGNS patients who underwent both tPSG and eHST post-operatively.

Methods: Data from 379 consecutive HGNS patients were retrospectively reviewed. Inclusion requirements were a pre-operative sleep study, a post-operative tPSG, and then an eHST, which at our institution is a type 3 home study. AHI mean and differences were calculated. Wilcoxon rank sum tests were used to analyze differences between tPSG and eHST. Sher₁₅ criteria (post-operative AHI≤15 events/hour and ≥50% reduction from baseline) was calculated and compared by χ² tests.

Results: Ultimately 61 patients met inclusion criteria with an average pre-operative AHI=33.2. When comparing the subject's tPSG versus eHST, tPSG AHI was significantly lower (AHI=8.8 versus AHI=17.6; respectively, p<0.001). There was also a difference in the percentage of patients that met Sher₁₅ criteria when using tPSG (80.3%) versus eHST AHI (45.9%).

Conclusions: HGNS patient's postoperative tPSG AHI was significantly lower than their eHST outcome. This work highlights the importance of reporting the type of post-operative study used in evaluating HGNS efficacy and the need for single amplitude, full-night studies to assess HGNS efficacy more accurately.