OSPREY Trial Suggests THN Therapy Effective in Moderate to Severe OSA

Ofer Jacobowitz, MD, PhD

New insights on the potential of the OSPREY trial suggested that targeted hypoglossal nerve stimulation (THN) therapy could be safe and efficacious for moderate to severe obstructive sleep apnea (OSA).

The details were presented at the American Thoracic Society 2020 International Conference in San Francisco.

Obstructive sleep disorder is a condition believed to affect over 1 million people globally, with 35 million of those cases originating from the United States.

Though therapeutic options such as positive airway pressure (PAP) have been known to correct sleep disordered breathing, they are not always tolerated.

Additionally, the implications of OSA on cardiovascular and neurocognitive outcomes have raised concerns among clinicians for decades.

Meanwhile, oral appliances and surgery are optional but generally less effective strategies in combatting OSA. Thus, an unmet need for therapeutic options exists.

Previously, investigators led by Ofer Jacobowitz, MD, PhD, Co-director of Sleep at ENT and Allergy Associates in New York, suggested THN therapy could be used to treat OSA, believing in to be “a simpler approach than incumbent technology with no sensor and an easier, proximal electrode implantation”.

With the present investigation, the team intended to design a confirmatory randomized clinical trial (RCT) of THN therapy for Level 1 evidence in moderate to severe OSA. 

Jacobowitz and colleagues first reviewed primary efficacy endpoints and potential study designs from THN3, which was the RCT of HGNS in OSA to report results.

Apnea hypopnea index (AHI) response rate (RR) was prioritized as the obligatory primary outcome for regulatory approval.

As such, THN3 AHI RRs for the treatment and control groups were 52% and 20%, respectively,

The team selected a parallel-arm RCT, of which all subjects were implanted, with 2/3 are activated at Month 1 (treatment group) and 1/3 activated at Month 7 (control). 

Patients were followed for a total of 13 months, with the primary endpoint being the difference in AHI RR between Treatment and Control groups at Month 7.

Secondary endpoints included quality of life instruments such as the Epworth Sleepiness Scale; Functional Outcomes of Sleep Questionnaire, EQ- 5D, SF-6D and PROMIS sleep questionnaires, and oximetry metrics (Oxygen Desaturation Index, and the percentage of sleep time below 90% oxygen saturation). 

Notably, OSPREY followed an adaptive “Goldilocks” Bayesian design that optimized the required number of subjects with the need for high-confidence inferences from results, according to the investigators.

A maximum of 150 subjects were allowed, and simulations predicted a study power of >95% for the primary endpoint.

Interim analyses would begin once 50 patients were randomized, recurring after each 20 additional randomizations up to 150.

Predictive probabilities based on accrued results would enable detection of early success or early futility.

Investigators concluded that the OSPREY trial would be “ a unique, efficient RCT that should provide high-confidence confirmation of the safety and efficacy of THN therapy in moderate to severe OSA.”