Use of a mandibular advancement device (MAD) proved non-inferior to guideline-recommended continuous positive airway pressure (CPAP) to reduce blood pressure in patients with hypertension and obstructive sleep apnea (OSA), in a randomized trial.
“These findings suggest that MAD could be considered an alternative to CPAP for optimizing blood pressure control in OSA patients with hypertension and high cardiovascular risk,” the researchers conclude.
“Looking at the totality of evidence available in the literature, it is still reasonable to say that CPAP is the first-line treatment until we have more data on the MAD,” said Ronald Lee Chi-Hang, MD, professor of medicine at Yong Loo Lin School of Medicine, National University of Singapore, who presented the results.
“However, for patients who truly cannot tolerate or accept using a CPAP, we should be more open-minded in looking for an alternative therapy such as a MAD, which based on our study, numerically had a better blood pressure reduction in patients compared with a CPAP,” said Dr. Chi-Hang, who is also a senior consultant in the Department of Cardiology at Singapore’s National University Heart Centre.
The results were presented April 6 at the American College of Cardiology Scientific Sessions 2024 and published online simultaneously in the Journal of the American College of Cardiology
Oral Appliance
OSA is increasingly recognized as “an underdiagnosed and modifiable cause of hypertension,” the researchers note in their report. “Patients with OSA develop recurrent collapse of the upper airway during sleep, resulting in hypoxemia, sympathetic hyperactivity, and BP surges.”
Current guidelines recommend screening and treatment of OSA in patients with hypertension, and CPAP is considered first-line therapy, they note.
“Despite being effective, unfortunately, many patients decline to use a CPAP or find it challenging to stick to the therapy,” Dr. Chi-Hang said, particularly those without daytime sleepiness.
MADs are oral appliances that work by advancing the mandible about 5 to 10 mm during sleep, he said. They provide an alternative to OSA patients and have been shown to improve daytime sleepiness and quality of life, “and in general, is better accepted and tolerated than CPAP.”
However, early studies are small, with short follow up, included patients with and without hypertension, and didn’t specify BP reduction as the primary outcome.
The CRESCENT trial was an investigator-initiated, randomized, non-inferiority trial that aimed to compare the relative effectiveness of MAD vs CPAP in reducing 24-hour ambulatory blood pressure in patients with moderate-to-severe OSA, hypertension and high cardiovascular risk. The prespecified margin for non-inferiority was 1.5 mm Hg.
A total of 321 participants were recruited at three public hospitals for polysomnography. All were older than age 40 years, had hypertension, and were at increased cardiovascular risk. Of these, 220 with moderate-to-severe OSA, defined as an apnea–hypopnea index (AHI) of ≥ 15 events/hour, were randomly assigned to either MAD or CPAP treatment.
The primary outcome was the difference between the 24-hour mean arterial BP at baseline and 6 months. The median age was 61 years, most patients (85.5%) were male, and all were Chinese. All had essential hypertension and were on one or more antihypertensive medications. Hypertension was relatively well controlled at baseline.
At 6 months, 24-hour mean arterial BP decreased by 2.5 mm Hg in the MAD group (P = .003) compared to no change from baseline in the CPAP group (P = .374).
The between-group difference was -1.6 mm Hg (95% CI, -3.51 to 0.24, non-inferiority P < .001).
There was a larger between-group reduction in all secondary ambulatory BP parameters in the MAD versus the CPAP group, with the most pronounced effects seen in the asleep BP parameters.
Both the MAD and CPAP significantly improved daytime sleepiness, with no between-group differences (P =.384). There were no between-group differences in cardiovascular biomarkers.
During the presentation, panel discussant Julie B. Damp, MD, associate professor of medicine at Vanderbilt Health in Nashville, Tennessee, called CRESCENT “a really interesting study, and I think it has a lot of information to add [regarding] what we know about this comparison in the literature, because this is a big study and it also followed these patients for longer than we’ve seen in some of the previous studies.”
Dr. Damp asked, however, about how these results might be extrapolated to other populations, since the vast majority of participants were male.
Dr. Chi-Hang pointed out that most OSA studies include mostly male patients, but noted that particularly in Asian culture, female patients may be more conservative in seeking treatment for problems with snoring, poor quality of sleep, or extensive daytime sleepiness. “Therefore, lots of times, even in clinical practice, we see that over 80 or 90% of patients are male patients,” he said.
Dr. Damp followed up by asking about the differential effectiveness of CPAP vs MAD. “Just in thinking about these two therapies, there is some evidence that the mandibular devices are potentially less effective on some of the sleep apnea-specific measures, so how much of this do you think is an issue of a better vs a not better treatment as opposed to an issue truly of compliance and what patients are able to tolerate?”
Dr. Chi-Hang agreed that in terms of reducing the AHI, CPAP is more effective than MAD. “In fact, in our data, the residual AHI was 10 for the MAD group and 2 for the CPAP group. Clearly, CPAP is more effective,” he said. “But the problem we are facing in this area is the value of AHI as an index is being questioned.”
AHI considers only the number of events, without taking into account the duration or the depth of the apnea, he said. “AHI is simply not an ideal index to document the disease severity,” or the impact on cardiovascular outcomes.