Certain traits can be used to identify patients with a type of obstructive sleep apnea that is highly responsive to oral appliance therapy, a recent secondary analysis of polysomnographic data suggests.
“While CPAP is great for some, there remains a large group of patients who really struggle with it,” Scott Sands, PhD, assistant professor of medicine at Harvard Medical School and Brigham and Women’s Hospital, said in a press release. “For these folks, this study highlights the potential benefit of measuring the underlying causes of their sleep apnea to estimate whether an oral appliance might be an equivalent or better choice over CPAP for the treatment of their sleep apnea.”
Sands and colleagues reviewed data on 93 patients from three parent studies, analyzing each participant’s loop gain, arousal threshold, lower ventilatory response to arousal, collapsibility and pharyngeal muscle compensation for association with the effectiveness of oral appliances and treatment response. Patients were placed into two groups based on a 50% reduction in the apnea-hypopnea index (AHI), with 54 falling into the predicted responder category and the remaining 39 falling into the nonresponder group.
To qualify for inclusion, patients were required to have a baseline polysomnography-derived AHI of 20 or more events per hour. Appliance efficacy, defined as the percent reduction in AHI with treatment relative to the baseline, was the primary outcome. Exclusion criteria for the reference studies included previous oral appliance usage, predominance of central sleep apnea at the baseline and oral appliance contraindications such as insufficient number of teeth, severe daytime sleepiness that requires urgent intervention and presence of periodontal disease, according to the researchers.
Results linked better appliance efficacy to favorable nonpharyngeal traits, such as moderate pharyngeal collapsibility, weaker muscle compensation, higher arousal threshold, lower arousal response and lower loop gain. Predicted responders, as compared with nonresponders, showed higher reduction in AHI from the baseline (73% vs. 51%; P < .0001) and lower treatment AHI (8 vs. 16 events per hour; P = .002), the researchers wrote.
Seventy-eight percent of the predicted responders group showed at least a 70% reduction in AHI. Overall, oral appliance treatment decreased AHI by a median of 67%. Cross-validation and adjusting for covariates, such as BMI, age, sex and neck circumference, did not alter the differences between the two groups, according to the study.
The average protrusion provided by the oral appliance was 89% of maximal mandibular protrusion. No associations were found between appliance efficacy and baseline AHI, age, sex, BMI or neck circumference. Additionally, baseline AHI was similar between responders (34 events per hour; 95% CI, 30-38) and nonresponders (33 events per hour; 95% CI, 29-37), the researchers reported.
“Further studies are needed to prospectively validate our predictive model for clinical use,” the researchers wrote. “We anticipate that identifying endotypes from routine diagnostic polysomnography will allow patient selection for oral appliance therapy in OSA.” – by Eamon Dreisbach
Disclosures: Sands and another author report they have served as consultants for Cambridge Sound Management, Inspire and Nox Medical. Sands reports he also serves as a consultant for Merck and receives grant support from Apnimed and Prosomnus. Please see the study for all other authors’ relevant financial disclosures.