High BMI lowers odds for nerve stimulation treatment response in OSA

Key takeaways:

• Hypoglossal nerve stimulation lowers obstructive sleep apnea severity in patients unable to use CPAP.
• Responses to this therapy differ based on BMI and sleep position.

Hypoglossal nerve stimulation reduced obstructive sleep apnea severity; however, this outcome was less likely among those with higher BMIs and those who slept in supine position, according to study results.

“Physicians can take both this new information about BMI and sleeping on your back vs. your side into consideration when counseling patients with OSA,” Eric C. Landsness, MD, PhD, assistant professor of neurology at Washington University School of Medicine, told Healio.

“I think this is an amazing treatment and is going to change the way we treat sleep apnea,” Landsness added. “I just want to make sure that it’s getting to the appropriate patients.”

In a single center retrospective cohort study published in JAMA Otolaryngology-Head & Neck Surgery, Landsness and colleagues evaluated 76 adults (median age, 61 years; 75% men; 93% white) with moderate to severe OSA implanted with hypoglossal nerve stimulation (HGNS) to determine if this therapy leads to treatment response, or at least a 50% decrease in preimplantation apnea-hypopnea index (AHI) score and an AHI score lower than 15 events per hour after implantation.

Researchers also sought to find out if achievement of treatment response differed by sleep position and BMI since 2023 HGNS eligibility thresholds include patients with severe obesity.

“Medicare guidelines extended this threshold to 35 [kg/m²] or less in 2020, and the U.S. Food and Drug Administration further expanded BMI eligibility criteria for HGNS to 40 [kg/m²] or less in 2023,” Landsness and colleagues wrote.

Included patients were intolerant to CPAP treatment.

Main findings

Within the total cohort, 78% (n = 59) met the study’s criteria for a treatment response to HGNS. Notably, researchers found an AHI lower than five events per hour after implantation in 49% (n = 37) of adults.

Before HGNS implantation, the median AHI was 29.3 events per hour, and this dropped to 5.3 events per hour after HGNS implantation, signaling a clinically meaningful response.

Most of the study population (84%; n = 64) had a BMI of 32 kg/m² or lower, whereas the remaining 16% (n = 12) had a BMI between 32 kg/m² and 35 kg/m².

The odds for HGNS treatment response decreased among those with a higher BMI of 32 kg/m² to 35 kg/m² vs. 32 kg/m² or lower (adjusted OR = 0.25; 95% CI, 0.07-0.94) during multivariable logistic regression analysis that considered the number of post implantation studies.

In addition to this finding, Landsness told Healio every rise in BMI by 1 unit reduced a patient’s likelihood of responding to the therapy by 17% (OR = 0.83; 95% CI, 0.68-1.01).

“It really was surprising to me how predictive BMI was of response to this treatment,” he said.

Only 39% (n = 17 of 44) of those who reported sleeping in supine position met the study’s criteria for a treatment response to HGNS, including 12 adults with a supine AHI lower than five events per hour.

“If a patient is very much a back sleeper only, they need to know that [HGNS] may not be as effective,” Landsness said.

Before therapy implantation, the median supine AHI score was 46.3 events per hour, which went down to 21.8 events per hour after implantation. This change was clinically meaningful, according to researchers.

Following adjustment for sleep position after implantation, researchers again found a reduced likelihood for HGNS treatment response with BMI based on supine AHI (aOR = 0.39; 95% CI, 0.04-2.59) but noted an “imprecision in the estimates.”

As a witness of patient reactions to this treatment, Landsness said the benefits linked to HGNS therapy change the lives of those with OSA.

“I had multiple instances when I tell the patient the good news that it works, that they almost break into tears of joy saying this has really revolutionized their life, and they’re so appreciative of it,” he said.

Lack of financial bias, future studies

Unlike past studies on HGNS, this study is free of financial bias, Landsness told Healio.

“I think that everyday clinicians should see this as much more trustworthy and more willing to embrace this treatment knowing that we don’t have any financial conflict of interest and this is in a real-world situation,” he said.

When asked about future studies, Landsness said it is important to look at the impact of HGNS in a more racially diverse population and to determine if there are other predictive factors that change how a patient responds to the therapy.

He added that researchers should also assess the impact of this therapy on diseases that patients have in addition to OSA to see if it benefits particular subpopulations.

Reference:

• Nerve stimulation for sleep apnea is less effective for people with higher BMIs. https://medicine.wustl.edu/news/nerve-stimulation-for-sleep-apnea-is-less-effective-for-people-with-higher-bmi/. Published April 4, 2024. Accessed April 4, 2024.