Patients with BMI Over 32 Respond Less to Hypoglossal Nerve Stimulation for OSA

Rutwik M. Patel, DO

Credit: Cox Health

Patients with a body mass index (BMI) of 32 to 35 have 75% lower odds of responding to hypoglossal nerve stimulation (HGNS) for obstructive sleep apnea (OSA) compared to patients with a BMI of ≤ 32.¹

Beyond continuous positive airway pressure (CPAP), the most effective treatment for OSA, HGNS, serves as a potential alternative therapy.² Patients may want to refrain from using CPAP since the device can be loud and uncomfortable.

HGNS was originally only approved for people with BMIs in a healthy range (18.5 – 24.9) before being extended to severely obese patients (BMIs up to 40) in recent years. Although the expanded BMI eligibility criteria intended to increase access to the therapy, the new research discovered the therapy’s effectiveness drops significantly with an increased BMI.

“Our study shows that the more overweight you are, the less likely it is that nerve-stimulation treatment will be effective in treating your sleep apnea,” said investigator Eric C. Landsness, MD, PhD, from Washington University School of Medicine, in a press release. “I’m not saying that we shouldn’t put this device in patients with a BMI of 38 or 40. But my job as a physician is to help overweight patients make an informed decision, to better understand their odds of success and realize that the chances of it working for them may be a lot less.”

Previously, limited research had been completed on the efficacy of HGNS for different BMI ranges.¹ To understand the association between HGNS and BMI, investigators conducted a cohort study to assess whether HGNS is an effective treatment for OSA, whether HGNS can treat supine OSA, and whether there is a link between BMI and treatment response. The team analyzed the data from January 2023 to January 2024, using a multivariable logistic regression to assess associations between HGNS treatment response and both BMI and supine sleep.

The retrospective cohort study, led by Rutwik M. Patel, DO, from Washington University School of Medicine, included 76 adult patients with OSA implanted with HGNS at the Washington University Medical Center in St Louis from April 2019 to January 2023. Of the sample, 75% were male, 93% were White, and the median age was 61 (51 – 68) years old. The primary outcome was a response to HGNS, using the modified Sher criteria.

Patel and colleagues defined treatment response as having ≥ 50% reduction in the preimplantation Apnea-Hypopnea Index (AHI) and a post-implantation AHI of < 15 events per hour. In total, 78% of patients achieved a treatment response, with a clinically meaningful reduction in median AHI from 29.3 events per hour preimplantation to 5.3 events per hour post-implantation (Hodges-Lehman difference of 23.0; 95% confidence interval [CI], 22.6-23.4).

The adjusted analysis found patients with a BMI of 32 to 35 had 75% lower odds of responding to HGNS compared to those with a lower BMI of ≤ 32 (odds ratio [OR], 95% CI, 0.07 – 0.94). As for the 44 patients who slept in a supine position, 39% achieved a treatment response, with a clinically meaningful reduction in median supine AHI from 46.3 events per hour preimplantation to 21.8 events per hour post-implantation (Hodges-Lehman difference of 24.6; 95% CI, 23.1 – 26.5).

“Our study shows an almost linear relationship between BMI and treatment success,” Landsness said.² “For every unit of BMI increase over 32, the odds of successful treatment decrease by about 17%.”

Additionally, the adjusted analysis showed BMI was linked to lower odds of responding to HGNS with supine AHI treatment response (OR, 0.39; 95% CI, 0.04 – 2.59).¹ However, the “imprecision of the estimates” makes this finding being unable to be concluded.

“This lack of precision is likely due to supine AHI score only being available for 8 patients with a BMI greater than 32,” investigators wrote. “However, the 61% reduction of odds of treatment success among patients with a BMI of 32 to 35 remains suggestive of an association between BMI and treatment response.”

Investigators noted limitations including survivorship bias (which could have led to an underreporting of adverse events), 18 patients that were lost to follow-up, the lack of subjective rating scales to show objective changes in AHI, the inability to evaluate the response of rapid eye movement dependent OSA to HGNS, and limited data of the severity of the preimplantation OSA. Additionally, most of the sample were males and non-Hispanic White patients, so the results should be viewed with caution.

“We have patients coming to us who really want this treatment because they view it as a life-changing alternative to CPAP,” Landsness said.² “It certainly can work for some people, but we don’t want to recommend it to patients if there’s a chance their BMIs will affect the device’s usefulness.”

^References

1. ^{Patel RM, Wang HZ, Jamro EL, et al. Response to Hypoglossal Nerve Stimulation Changes With Body Mass Index and Supine Sleep. JAMA Otolaryngol Head Neck Surg. Published online April 4, 2024. doi:10.1001/jamaoto.2024.0261}
2. ^{Nerve Stimulation for Sleep Apnea Is Less Effective for People With Higher BMIs. EurekAlert! April 4, 2024. https://www.eurekalert.org/news-releases/1039881. Accessed April 9, 2024.}