Oral appliances that treat obstructive sleep apnea (OSA) by moving the lower jaw forward appear to improve sleep, but they don’t reduce key risk factors for developing heart and other cardiovascular diseases, according to a multiuniversity and multihospital team of researchers in France.
In a randomized controlled trial of 150 patients with severe sleep apnea and no overt cardiovascular disease, subjects received either a mandibular advancement device (MAD) or a sham oral appliance. While MAD therapy significantly improved apnea-hypopnea index (AHI) scores, microarousal index scores, snoring, fatigue, and sleepiness, it did not improve endothelial function, a key predictor of cardiovascular disease, or lower blood pressure.
Continuous positive airway pressure, more commonly known as CPAP, is considered the gold standard of OSA treatment. Yet many patients find it uncomfortable, and MAD is the most commonly prescribed alternative.
“Endothelial dysfunction is one of the intermediate mechanisms that potentially contribute to the increased risk of cardiovascular disease in OSA,” said lead author Frédéric Gagnadoux, MD, professor of pulmonology at the University Hospital of Angers. “Whether MAD therapy improves endothelial function in OSA patients had not been evaluated before in properly controlled and adequately powered trials.”
Subjects had an AHI, which measures the number of apnea and hypopnea events per hour of sleep, greater than or equal to 30. They ranged in age from 18 to 70 years, and 86% were men. None had signs of cardiovascular disease. Although their AHI scores indicated severe sleep apnea, they reported only mild daytime sleepiness. Compliance with using MAD during the 2-month study was high, as verified by researchers using a tiny embedded monitor.
“Our study demonstrates the effectiveness of MAD therapy in reducing sleep disordered breathing and improving related symptoms in patients with severe OSA who do not tolerate CPAP,” said Gagnadoux. “Despite being affected by severe OSA, our patients’ reactive hyperemia index, a validated marker of endothelial function, was within the normal range at baseline.”
Further studies are needed to determine whether MAD therapy can improve endothelial function in OSA patients who exhibit endothelial dysfunction when they enroll or have overt signs of cardiovascular disease or metabolic disorders, Gagnadoux said.
Also, the researchers noted that their negative findings on blood pressure outcomes should not be generalized to all OSA patients because study participants shared characteristics associated with lower blood pressure reductions in response to OSA therapy, including a low prevalence of hypertension and mild daytime sleepiness.
The study, “Impact of Mandibular Advancement Therapy on Endothelial Function in Severe Obstructive Sleep Apnea,” was published by the American Journal of Respiratory and Critical Care Medicine.