麻豆传媒

SEATTLE -- With 36 months of follow-up, efficacy of an upper airway stimulation (UAS) device for obstructive sleep apnea was maintained in participants in the product's pivotal trial, its principal investigator said here.

Objective response rates and patients' and their bed-partners' own assessments seen among participants with complete data 36 months after device placement were nearly identical to those reported at 12 months, when the trial's primary evaluations were made, according to , medical director of the Sleep Medicine Center at the University of Pittsburgh Medical Center.

Although the treatment fell well short of a cure -- some degree of apnea persisted in half of patients, and about one-quarter did not show clinically significant improvement at 36 months -- Strollo said it was encouraging to see that the responses achieved in the first year were, for the most part, sustained for an additional 2 years.

He presented the data in a platform session at , the annual conference of the Associated Professional Sleep Societies.

The UAS device, approved last year and sold by Inspire Medical Systems, is an implanted neurostimulator with a lead connected to the hypoglossal nerve under the chin, plus a sensor lead in the chest to coordinate stimulation with breathing. The nerve stimulation forces the tongue to move forward, pulling the airway into a more open configuration and preventing collapse. The product is indicated for sleep apnea patients who have not responded to or are intolerant of continuous positive airway pressure.

Primary outcome data in the uncontrolled STAR (Stimulation Therapy for Apnea Reduction) trial after 12 months were reported in the New England Journal of Medicine in January 2014, following preliminary presentation at SLEEP 2013. At that evaluation, median apnea/hypopnea index (AHI) values fell 68% from baseline in the 126 treated patients. Similar improvements were seen in the oxygen desaturation index.

At 36 months, Strollo said here, 74% of the 98 STAR patients who completed polysomnography had a clinical response, defined as an AHI decrease of at least 50% to a value less then 20 events/hour. AHI values less than 5, usually interpreted as no apnea, were found in 44% of patients, while 69% had values less than 10 -- both the same or greater than at 12 months.

About 90% of these 98 patients had met criteria for clinical response at least once during the study, Strollo noted.

Strollo devoted most of his presentation here to patient-reported outcomes, assessed with the Functional Outcomes of Sleep Questionnaire (FOSQ) and Epworth Sleepiness Scale, for which data were available from 116 of the original 126 STAR participants.

Scores on those instruments had both shown improvement from baseline to 12 months, and the values in the primary analysis were maintained through the 36-month assessment (both P<0.05 for 36 months versus baseline), he reported:

• Mean FOSQ: 14.3 baseline, 17.3 at 12 months, 17.4 at 36 months
• Mean Epworth: 11.6 baseline, 7.0 at 12 months, 7.0 at 36 months

Median values were also essentially unchanged from 12 to 36 months, Strollo reported.

Improvements seen at 12 months in snoring, as rated separately by participants and their bed-partners, were also sustained through the 36-month evaluation.

At baseline as reported by partners, for example, 36% said it was generally disruptive enough that they left the bedroom, and another 24% rated it as "very intense."

These values declined to 5% and 3% at 12 months, respectively, and to 3% and 2% at 36 months. At the other end, the proportion of partners reporting no snoring rose from 6% at baseline to 48% at 12 months and 44% at 36 months.

But , co-director of the UHealth Sleep Medicine Program at the University of Miami, told 麻豆传媒 that he was still skeptical of the system. He noted that one patient had died during the initial STAR trial -- albeit of causes the investigators determined were not related to the device -- while many patients failed to benefit to a clinically significant degree. When it's presented that way, he said, "what is a patient going to say?"

In fact, Strollo presented some additional safety data from the long-term follow-up. An additional two patients died, also of causes ruled unrelated to the device, and the device had to be removed from one patient due to septic arthritis. Another patient electively decided to have it removed.

He did not discuss other, less severe adverse events. In the earlier reports from the STAR trial, patient complaints about tongue immovability were noted.

During the question period after Strollo's presentation, one audience member noted that the device is approved only for patients with body mass index values up to 32, and asked whether an expansion to more obese patients was in the offing.

Strollo said the current limitations arose from the STAR trial's exclusion of patients with BMIs greater than 32. But he added that, in Europe, the device is approved for patients with BMI values up to 35, so data in this population should eventually become available.

Another important limitation to the system's approval is that it is contraindicated in patients with complete concentric collapse at the level of the soft palate during endoscopy under anesthesia. Going into STAR, Strollo and colleagues had determined that the system would be less likely to work in such patients and so they were excluded.

In conjunction with the BMI limitations and other exclusions, therefore, only about 15% of CPAP-resistant sleep apnea patients screened for STAR were accepted into the trial -- a number that probably reflects the eligibility for the UAS device in clinical practice.

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