DENVER (FRONTLINE MEDICAL NEWS) – The surgically implanted Inspire system for controlled upper airway stimulation as therapy for moderate to severe obstructive sleep apnea demonstrated sustained benefit at 42 months of prospective follow-up in the STAR trial, Dr. Patrick J. Strollo Jr. reported at the annual meeting of the Associated Professional Sleep Societies.

STAR was the pivotal trial whose previously reported 12-month outcomes led to Food and Drug Administration clearance of the device. Dr. Strollo was first author of that paper ( N Engl J Med. 2014 Jan 9;370:139-49 ). At SLEEP 2016, he presented patient- and partner-reported outcomes at 42 months. Bottom line: The device had continued safety and no loss in efficacy.

“So far it seems to be a useful option for people who frequently didn’t have an option. And the technology is improving and will only get better,” said Dr. Strollo, professor of medicine and clinical and translational science, director of the Sleep Medicine Center, and codirector of the Sleep Medicine Institute at the University of Pittsburgh.

The Inspire system consists of three parts implanted by an otolaryngologist in an outpatient procedure: a small impulse generator, a breathing sensor lead inserted in the intercostal muscle, and a stimulator lead attached to the distal branch of the 10th cranial nerve, the hypoglossal nerve controlling the tongue muscles.

The device is programmed to discharge at the end of expiration and continue through the inspiratory phase, causing the tongue to move forward and the retrolingual and retropalatal airways to open, he explained in an interview.

Upper airway stimulation is approved for commercial use in patients such as those enrolled in the STAR trial on the basis of pilot studies that identified most likely responders. The key selection criteria include moderate to severe obstructive sleep apnea as defined by an apnea-hypopnea index of 20-50, nonadherence to continuous positive airway pressure (CPAP), a body mass index of 32 kg/m2 or less, and absence of concentric collapse of the airway at the level of the palate during sedated endoscopy.

STAR included 126 participants who received the upper airway stimulation device. There have been two explants: one from septic arthritis, the other elective.

A total of 97 STAR participants had 42-month follow-up data available. Among the key findings were that:

• Mean scores on the Epworth Sleepiness Scale decreased from 11.6 at baseline to 7 at 12 months and 7.1 at 42 months.

• Scores on the Functional Outcomes of Sleep Questionnaire improved from 14.3 at baseline to 17.3 at 12 months and 17.5 at 42 months.

• The scores on both the Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire were abnormal at baseline and converted to normal range at both 12 and 42 months of follow-up.

• At baseline, 29% of the patients’ sleeping partners characterized the snoring as loud, 24% rated it ‘very intense,’ and 30% left the bedroom. At 32 months, 11% of partners called the snoring loud, 3% deemed it very intense, and only 4% left the room.

• At 42 months, 81% of patients reported using the device nightly. That’s consistent with the objective evidence of adherence Dr. Strollo and his coinvestigators obtained in a study of postmarketing device implants in which they found device usage averaged about 7 hours per night.

“That’s much better than we see with CPAP in patients who can tolerate that therapy,” Dr. Strollo observed.

The planned 5-year follow-up of STAR participants includes a full laboratory polysomnography study to obtain objective apnea-hypopnea index figures.

The other major development is the launch of a comprehensive registry of patients who receive a post-marketing commercial implant. Roughly 1,000 implants have been done worldwide to date, but now that the device is approved, that number will quickly grow. The registry should prove a rich source for research.

“The goal is to try to refine the selection criteria,” according to Dr. Strollo.

Given that only about 50% of patients with moderate to severe sleep apnea are able to tolerate CPAP long term, where does the Inspire system fit into today’s practice of sleep medicine?

“Upper airway stimulation is another tool, another option for patients,” he said. “In my practice, normally I’d let patients try positive pressure first. I want to make sure they’ve tried CPAP, and they’ve tried more advanced therapy like autotitrating bilevel positive airway pressure, which is more comfortable than CPAP. Bilevel positive airway pressure allows you to salvage a fair number of patients who can’t tolerate CPAP. And I also offer an oral appliance, although the robustness of an oral appliance is not great as apnea becomes more severe.”

The STAR trial is supported by Inspire Medical Systems. Dr. Strollo reported receiving a research grant from the company.


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