Polysomnography can be used in people with obstructive sleep apnoea to identify five traits that predict a good response to oral appliances, research shows.
The pharyngeal traits of collapsibility and muscle compensation and non-pharyngeal traits of loop gain, arousal threshold and ventilatory response to arousal could be used to target people for first line oral appliance therapy, according to a multicentre study that included researchers from the Sleep Research Group, Charles Perkins Centre, The University of Sydney.
“Since oral appliances work by improving the collapsibility of the upper airway, patients without really severe collapsibility are more likely to benefit from an oral appliance, while those with sleep apnea caused by other traits, such as exaggerated reflex responses to drops in oxygen levels, are less likely to benefit,” the researchers wrote in the Annals of the American Thoracic Society.
Their study involving 93 patients with moderate to severe OSA (baseline apnoea-hypopnea index [AHI] ≥20 events/hr) examined whether routine diagnostic polysomnography-estimated OSA traits were associated with oral appliance efficacy and could predict response to treatment (based on 50% reduction in AHI).
Greater oral appliance efficacy was associated with favourable non-pharyngeal traits (lower loop gain, higher arousal threshold and lower response to arousal), moderate (non-mild, non-severe) pharyngeal collapsibility and weaker muscle compensation (overall R2=0.30, adjusted R2=0.19, p=0.003).
The study authors said that when combined, these traits identified a group of about 60% of patients (n=54) who were predicted responders, compared with a smaller group 9n= 39) of predicted non-responders. The responders exhibited a significantly greater reduction in AHI from baseline (73% vs 51%) and a lower treatment AHI (8 vs. 16 events/hr).
Notably, the differences in response were seen after adjusting for factors including baseline OSA severity, obesity and neck circumference)
“Surprisingly, it didn’t seem to matter whether sleep apnoea was moderate or very severe,” commented study co-investigator Dr Scott. Sands, Scott Sands, PhD, assistant professor of medicine at Harvard Medical School and Brigham and Women’s Hospital.
“Oral appliance therapy was remarkably effective in some quite overweight patients with very severe OSA.”
The study authors said that if validated in other studies, the traits could be used to identify a subgroup of OSA patients who show good treatment efficacy with oral appliances.
“When coupled with the reported high adherence to [oral appliance] therapy, this appears sufficient to justify offering oral appliances as a first-line therapy in selected (moderate-to-severe) OSA patients,” they wrote.
Dr Sands said that once the most useful measures for predicting patient outcomes are established, he believes they will be readily incorporated into routine sleep recording systems.
“While CPAP is great for some, there remains a large group of patients who really struggle with it,” he said.
“For these folks, this study highlights the potential benefit of measuring the underlying causes of their sleep apnoea to estimate whether an oral appliance might be an equivalent or better choice over CPAP for the treatment of their sleep apnoea.”