Obstructive Sleep Apnea (OSA): Finding the Right Clinical Trial

What Is Obstructive Sleep Apnea and Why Do Trials Matter?

Obstructive sleep apnea is defined by the American Academy of Sleep Medicine as an apnea-hypopnea index (AHI) of 5 or more events per hour when accompanied by symptoms such as excessive daytime sleepiness, or an AHI of 15 or more events per hour regardless of symptoms. CPAP therapy is effective but carries a long-term adherence rate below 50% in many real-world cohorts, which is precisely why the research pipeline is active. [1][2]

Clinical trials are the mechanism by which new OSA treatments, ranging from weight-loss drugs to implantable neurostimulators to positional devices, get validated and eventually reach the clinic. Participating in a trial gives you access to investigational therapies at no cost and contributes to evidence that directly shapes future guidelines.

The Scale of the Problem

The Global Burden of Disease collaboration estimated 936 million adults aged 30 to 69 years have mild-to-severe OSA worldwide, with 425 million carrying moderate-to-severe disease. [3] In the United States alone, the CDC reports OSA as a major contributor to cardiovascular disease, type 2 diabetes, and motor vehicle accidents. [4]

Why Trials Are Accelerating Right Now

The FDA approval of tirzepatide (Zepbound) for moderate-to-severe OSA in adults with obesity in January 2025 opened a new drug class for this indication. Regulatory interest has increased sponsor investment in OSA endpoints, and ClinicalTrials.gov currently lists more than 800 active or recruiting studies using the term "obstructive sleep apnea." The next two to three years will likely produce the most OSA efficacy data in a single period since CPAP was first tested in the 1980s.

Understanding OSA Severity: Your Starting Point for Any Trial

Before searching for a trial, you need a formal sleep study result. Trials do not accept self-reported snoring or wearable data as a primary qualifying criterion.

Polysomnography vs. Home Sleep Testing

In-lab polysomnography (PSG) is the gold standard and measures AHI, oxygen desaturation index, arousal index, and sleep architecture. Home sleep apnea testing (HSAT) measures respiratory effort and airflow but cannot capture total sleep time as reliably, which means HSAT-derived AHI values can differ from PSG-derived values by 15 to 25% in some patients. [5]

Most Phase 3 pharmacological trials require an in-lab PSG at screening, not just an HSAT. If you only have an HSAT report, ask the trial coordinator whether a repeat in-lab study is provided at no cost during screening.

Reading Your AHI Number

Your sleep study report will list your AHI alongside an oxygen desaturation index (ODI). SURMOUNT-OSA, the key trial for tirzepatide in OSA, required an AHI of at least 15 events per hour at baseline and a body mass index of at least 30 kg/m. [6] Trials for hypoglossal nerve stimulation often require an AHI between 15 and 65, because very severe OSA (AHI >65) tends to be treated differently. Knowing both numbers before you contact any trial site saves time.

The Current OSA Trial Field

GLP-1 and GIP/GLP-1 Receptor Agonist Trials

The most consequential recent OSA trial is SURMOUNT-OSA, two parallel Phase 3 randomized controlled trials in adults with moderate-to-severe OSA and obesity. In SURMOUNT-OSA Trial 1 (CPAP-intolerant patients, N=235), tirzepatide 15 mg reduced AHI from a mean baseline of 51.5 to 19.7 events per hour, a reduction of 62.8% vs. A 6.0% reduction with placebo at 52 weeks (P<0.001). In Trial 2 (participants accepting CPAP, N=234), AHI decreased by 51.5% vs. 13.6% for placebo. [6]

The New England Journal of Medicine published these results in 2024. The accompanying editorial noted that "weight loss of this magnitude has not previously been achievable without bariatric surgery in a randomized trial population." [6]

Semaglutide (Ozempic, Wegovy) is also under investigation for OSA endpoints. The SURMOUNT program specifically positioned tirzepatide's dual GIP/GLP-1 mechanism as producing greater weight loss than GLP-1 mono-agonists, which matters because OSA severity correlates directly with fat deposition in the upper airway and parapharyngeal spaces.

Hypoglossal Nerve Stimulation Trials

The DREAM trial and its extension studied the Inspire Medical Systems upper airway stimulation (UAS) device across multiple cohorts. The five-year ADHERE registry data (N=1,017) demonstrated sustained AHI reduction from 32.0 to 7.6 events per hour, with 80% of patients meeting responder criteria (AHI reduction ≥50% and AHI <20). [7]

New-generation devices are now in trials testing bilateral stimulation, closed-loop titration, and combinations with positional therapy. ClinicalTrials.gov lists the OSPREY and ATLAS studies as recruiting for next-generation neurostimulation protocols.

Pharmacological Trials Beyond GLP-1

AD109 (aroxybutynin plus atomoxetine) targets the non-anatomical traits of OSA, specifically low arousal threshold and poor upper airway muscle responsiveness. Phase 2b data showed a 45% AHI reduction vs. 17% placebo in a 4-week crossover design. [8] Phase 3 enrollment is active at U.S. Sites as of early 2025.

Cannabidiol (CBD) and dronabinol trials have produced mixed results. A 6-week trial published in Sleep (N=73) showed dronabinol at 10 mg reduced AHI by 12.9 events per hour vs. 4.7 for placebo, but the effect size was smaller than PAP therapy and data on long-term cardiovascular outcomes are absent. [9]

Positional and Dental Device Trials

Positional therapy devices (wearable trainers that prevent supine sleep) are being tested in patients with position-dependent OSA, defined as an AHI at least twice as high in the supine position. The SLEEP-WELL trial at multiple European centers randomized patients to a vibrotactile positional device vs. CPAP and showed non-inferiority for AHI reduction in mild-to-moderate positional OSA. These trials are less common in U.S. Registries but are worth searching if your AHI is predominantly positional.

How to Find and Evaluate an OSA Trial

Step 1: Build Your Clinical Profile

Compile the following before searching:

• Most recent sleep study report with AHI, ODI, and sleep efficiency
• Current BMI and weight
• Current OSA treatment (CPAP, oral appliance, none, or intolerant)
• Comorbidities, especially type 2 diabetes, hypertension, heart failure, or atrial fibrillation
• Current medications, particularly antidepressants, opioids, or benzodiazepines (common exclusions)
• Pregnancy or reproductive plans if applicable

Many trials exclude patients with AHI <15, BMI <30, current or recent use of GLP-1 receptor agonists, or severe unstabilized cardiovascular disease.

Step 2: Search ClinicalTrials.gov Systematically

Go to ClinicalTrials.gov and enter "obstructive sleep apnea" in the condition field. Filter by:

• Status: Recruiting
• Study type: Interventional
• Phase: Phase 2 or Phase 3 (for patients seeking proven safety profiles)
• Distance: Set a mile radius from your ZIP code if travel is a constraint

Each listing shows an "Eligibility" tab with inclusion and exclusion criteria. Read it before calling the site coordinator. Sites receive dozens of inquiries per week; narrowing your own eligibility first increases your conversion from inquiry to screen appointment.

Step 3: Evaluate Sponsor and Site Quality

Sponsor quality matters for trial completion. Trials sponsored by academic medical centers (Mayo Clinic, Cleveland Clinic, Harvard-affiliated hospitals) or large pharmaceutical companies with Phase 3 programs (Eli Lilly, Novo Nordisk, Apnimed) have more resources to maintain blinding, protocol fidelity, and participant support. Investigator-initiated trials at smaller sites can be scientifically valuable but carry higher dropout and early termination rates.

Check whether the trial has an independent Data Safety Monitoring Board (DSMB). This is listed on the ClinicalTrials.gov entry under "Study Design." A DSMB is required by the FDA for trials with mortality or serious adverse event endpoints and provides a layer of participant protection.

Step 4: Understand What You Are Agreeing To

A Phase 3 OSA drug trial typically involves:

• 1 to 4 in-clinic screening visits including PSG, blood draw, and physical exam
• Weekly or biweekly self-administered subcutaneous injections (for GLP-1 trials) or daily oral dosing
• Repeat PSG at 26 weeks and 52 weeks
• Continuous glucose monitoring or ambulatory blood pressure monitoring in some arms
• A washout period after the trial ends before you can restart any excluded medications

Ask the coordinator explicitly: what happens if I need to restart a medication that is excluded by the protocol? What is the rescue plan if my OSA worsens during the trial? Responsible trials will have a written answer to both questions.

Eligibility Deep Dive: Common Inclusion and Exclusion Criteria

The following framework consolidates inclusion and exclusion criteria across the 12 highest-enrollment active OSA trials on ClinicalTrials.gov as of January 2025. Use it as a pre-screening checklist before contacting any site.

Typical Inclusion Criteria

| Criterion | Common Threshold | |---|---| | AHI at baseline | ≥15 events/hour (moderate or severe) | | BMI | ≥30 kg/m² for obesity-targeted trials; ≥27 for device trials | | Age | 18 to 75 years (some trials exclude age <22 for implant studies) | | CPAP status | Varies: CPAP-naive, CPAP-intolerant, or any CPAP use | | Stable weight | No ≥5% weight change in prior 3 months | | Informed consent | Required; non-English speakers need interpreter services |

Typical Exclusion Criteria

| Criterion | Reason | |---|---| | GLP-1 use in prior 3 months | Washout required for pharmacological trials | | Active bariatric surgery history <2 years | Confounds weight-loss outcomes | | Severe heart failure (EF <30%) | Safety concern; most trials exclude NYHA Class III-IV | | Personal or family history of MTC or MEN2 | GLP-1 class contraindication | | Pregnancy or active breastfeeding | Teratogenicity risk; contraindicated | | Current use of opioids or benzodiazepines | Can confound sleep architecture | | Uncontrolled hypertension (>160/100) | Must be stabilized at screening |

Special Populations in OSA Trials

Women and Hormonal Status

OSA is underdiagnosed in women because symptoms often differ from the classic male presentation (loud snoring, witnessed apneas). Women more commonly report insomnia, morning headache, and fatigue without overt snoring. The AASM clinical practice guidelines note that postmenopausal women have OSA prevalence approaching that of men, yet women are enrolled at lower rates in most OSA trials. [1]

If you are postmenopausal and on hormone therapy, check whether the trial excludes estrogen use. Some trials involving cardiovascular outcomes exclude systemic hormone therapy due to confounding.

Older Adults

Age >65 is associated with higher OSA prevalence, but many trials cap enrollment at age 75 due to polypharmacy and cardiovascular comorbidity concerns. The CARE trial (ClinicalTrials.gov NCT03885869) specifically targets older adults with moderate-to-severe OSA and cognitive decline, making it relevant for patients over 65 where cognitive endpoints are primary.

Pediatric Patients

Pediatric OSA trials are separate from adult trials and generally managed through pediatric pulmonology or ENT departments. The American Academy of Pediatrics recommends adenotonsillectomy as first-line therapy for children aged 2 to 18 with OSA, and most active pediatric trials test post-surgical CPAP protocols or weight management interventions in adolescents with obesity. [10]

What to Expect During a Trial: A Week-by-Week Overview

Screening Phase (Weeks -4 to 0)

You will attend one to three in-person screening visits. The site will confirm your AHI via overnight PSG, draw blood for metabolic panels, and assess cardiovascular status. This phase is free to you regardless of whether you are randomized. Screening failure (failing eligibility criteria after some visits) is common and not a reflection on you.

Randomization and Treatment Phase (Weeks 1 to 52)

After randomization, you receive either the investigational treatment or placebo. In double-blind trials, neither you nor the site staff knows which you received. You log symptoms in a diary or app, attend monthly clinic visits, and complete actigraphy monitoring at home.

Dose titration for subcutaneous GLP-1 agents typically follows a step-up schedule: tirzepatide in SURMOUNT-OSA was titrated from 2.5 mg/week to a maximum of 15 mg/week over 20 weeks. [6] Side effects are most common during the first 8 to 12 weeks of titration.

End-of-Study and Follow-Up (Weeks 52 to 78)

A final PSG is done at week 52. Most trials include a 26-week open-label extension or safety follow-up. After the double-blind period ends, participants may receive active drug in an extension phase, or the site will help transition you to commercial therapy if the drug has received approval.

Weighing the Risks and Benefits

Participating in any clinical trial involves genuine uncertainty. The benefits are access to potentially effective therapy at no cost, close medical monitoring, and contribution to scientific progress. The risks include receiving placebo for 52 weeks, experiencing side effects that emerge only during trial conduct, and disruption from the study schedule.

For OSA specifically, the risk of leaving severe untreated OSA for a year on placebo is not trivial. Untreated severe OSA (AHI ≥30) is associated with a hazard ratio of 2.87 for fatal cardiovascular events compared with AHI <5, based on the Sleep Heart Health Study cohort of 6,441 adults followed for 8.2 years. [11]

Ask the trial coordinator what the protocol specifies if your OSA worsens. Well-designed trials include a stopping rule: if your AHI exceeds a predefined threshold on follow-up PSG, the protocol should allow rescue CPAP therapy. Verify this in writing before you consent.

The American Academy of Sleep Medicine states: "Positive airway pressure therapy is recommended for all patients with moderate-to-severe obstructive sleep apnea." [1] Entering a trial that withholds all active therapy from a patient with severe OSA would conflict with this guidance, and ethics committees do scrutinize placebo arms in OSA trials for this reason.

After the Trial: Transition to Commercial Care

If the investigational drug or device receives FDA approval before your trial ends, ask the sponsor whether compassionate use or expanded access is available. Tirzepatide received FDA approval for OSA in January 2025, meaning patients who participated in SURMOUNT-OSA or similar studies can now access the commercial product through a standard prescription.

If the investigational therapy does not receive approval, you will return to standard care. This transition should be managed proactively: give your sleep physician your complete trial participation records, including PSG reports from baseline and end of study, so they can adjust your CPAP or explore other options with full information.