Use of Hypoglossal Nerve Stimulation for Treating OSA in Military Patient Populations
Background: Failure to effectively treat obstructive sleep apnea (OSA) and its symptoms is incompatible with military readiness. Continuous positive airway pressure (PAP) is the gold standard treatment for OSA, but it is impractical in austere environments. Another OSA treatment, hypoglossal nerve stimulation (HGNS), which is implanted, could have advantages for military patients but is unclear whether HGNS is efficacious.
Methods: We conducted a review of randomized controlled trials and controlled trials published from 2013 to 2023. Primary outcome measures included the Apnea-Hypopnea Index and Epworth Sleepiness Scale. The quality of evidence was assessed using a rating of 1 to 5 based on a modification of the Oxford Centre for Evidence-based Medicine Levels of Evidence and Grades of Recommendation.
Results: We identified 334 studies; 318 did not meet inclusion criteria. The remaining 16 articles were classified into 9 cohorts. Six articles were based on data from the STAR trial and 4 were based on data from a German postmarket long-term follow-up of upper airway stimulation for OSA efficacy. The remaining cohorts were smaller studies that examined moderate-to-severe OSA with nonadherence or failure, a randomized controlled crossover trial, and 1 direct comparator with PAP treatment.
Conclusions: HGNS feasibility in military settings has not been adequately studied, considering the specific demands of operational settings and patient demographics. Understanding risks and benefits specific to military context will help guide practices and determine the suitability of HGNS for OSA in diverse military settings.
TJU and UP Cohorts
The TJU and UP cohorts are composed of patients who underwent implantation between May 2014 and August 2016 at 2 academic centers.31,32 Selection criteria was consistent with that used in the STAR trial, and patients completed postoperative titration PSG and outpatient follow-up (48 patients at TJU and 49 at UP). Primary outcomes included AHI, ESS, and O2 nadir. Secondary outcomes consisted of surgical success and percentage of patients tolerating optimal titration setting at follow-up. Postoperative outcomes were assessed during the titration PSG. Time from initial ESS to postoperative PSG at TJU was 1.7 years and at UP was 1.9 years. Time from initial AHI to postoperative PSG at TJU was 90.4 days and 85.2 days at UP. At TJU, mean (SD) AHI and ESS dropped from 35.9 (20.8) and 11.1 (3.8), respectively at baseline to 6.3 (11.5) and 5.8 (3.4), respectively at follow-up. At UP, mean (SD) AHI and ESS fell from 35.3 (15.3) and 10.9 (4.9), respectively at baseline to 6.3 (6.1) and 6.6 (4.5), respectively at follow-up. There were no site-related differences in rates of AHI, ESS, or surgical success.31
Pordzik and Colleagues Cohort
This cohort of 29 patients underwent implantation between February 2020 and June 2022 at a tertiary university medical center with both pre- and postoperative PSG. Selection criteria was consistent with that of the German postmarket cohort. Postoperative PSG was completed a mean (SD) 96.3 (27.0) days after device activation. Mean (SD) AHI dropped from 38.6 (12.7) preoperatively to 24.4 (13.3) postoperatively. Notably, this cohort showed a much lower decrease of postoperative AHI than reported by the STAR trial and UP/TJU cohort.33
Stimulation vs Sham Trial
This multicenter, double-blinded, randomized, crossover trial assessed the effect of HGNS (stim) vs sham stimulation (sham) in 86 patients that completed both phases of the trial. Primary outcomes included AHI and ESS. Secondary outcomes included FOSQ. No carryover effect was found during the crossover phase. The difference between the phases was−15.5 (95% CI, −18.3 to −12.8) for AHI and −3.3 (95% CI, −4.4 to −2.2) for ESS.34
Comparator
The comparator study used propensity score matching to compare outcomes of HGNS and PAP therapy. Primary outcomes included sleepiness, AHI, and effectiveness with outcome measures of AHI and ESS collected at baseline and 12 months postimplantation. The article reported that 126 of 227 patients were matched 1:1. Both groups showed improvement in AHI and ESS. Mean (SD) AHI for the HGNS group at baseline started at 33.9 (15.1) and decreased to 8.1 (6.3). Mean (SD) ESS for the HGNS group at baseline was 15.4 (3.5) and decreased to 7.5 (4.7). In the PAP comparator group, mean (SD) baseline AHI was 36.8 (21.6) and at follow-up was 6.6 (8.0) and mean (SD) ESS was 14.6 (3.9) at baseline and 10.8 (5.6) at follow-up.35
DISCUSSION
The current clinical data on HGNS suggest that this treatment is effective in adults with moderate-to-severe OSA and effects are sustained at long-term follow-up, as measured by AHI reduction and improvements in sleep related symptoms and quality of life (Table 2). These results have been consistent across several sites.
The STAR trial included a randomized control withdrawal group, for whom HGNS treatment was withdrawn after the 12-month follow-up, and then restored at 18 months.21 This revealed that withdrawal of HGNS treatment resulted in deterioration of both objective and subjective measures of OSA and sleepiness. The beneficial effects of HGNS were restored when treatment was resumed.24 Additionally, the RCCT revealed that therapeutic stimulation via HGNS significantly reduced subjective and objective measures of OSA.34 These studies provide definitive evidence of HGNS efficacy.
Currently, a diagnosis of OSA on PAP is classified as a 50% military disability rating. This rating is based primarily on epidemiologic evidence that untreated OSA is a costly disease that leads to other chronic illnesses that increases health care utilization.9 HGNS requires an initially invasive procedure and higher upfront costs, but it could result in reduced health care use and long-term costs because of improved adherence to treatment—compared with CPAP—that results in better outcomes.
