Sleep apnoea mouthguard equal to CPAP in reducing hypertension

4 minute read

A mandibular advancement device is an effective alternative for those with CV risk who can’t or won’t tolerate CPAP.

A mandibular adjustment device was on par with CPAP in reducing 24-hour ambulatory blood pressure, a study in people with hypertension and obstructive sleep apnoea has found. 

The CRESCENT trial, led by Singaporean researchers, compared changes in blood pressure when using a mandibular advancement device (MAD) versus CPAP. 

“To the best of our knowledge, the CRESCENT trial is the largest randomized clinical trial on the comparative effectiveness of MAD versus CPAP for BP reduction,” wrote the authors in the Journal of the American College of Cardiology

“All participants had hypertension and a high risk of cardiovascular disease, and two-thirds of the participants had severe OSA. 

“With the median usage of 5.5 hours per night for the MAD group and 5.0 hours for the CPAP group, we found that MAD was non-inferior to CPAP for reducing 24-hour mean arterial BP at 6-month follow-up.” 

OSA is a modifiable cause of hypertension, which in turn is a major risk factor for cardiovascular and cerebrovascular diseases. Cardiology guidelines recommend treating OSA in patients with hypertension. 

CPAP is recommended as the first-line treatment for OSA but has low levels of acceptance and adherence, with research showing that one in four patients stop their use within a year

The non-inferiority study randomised 220 people aged over 40 years who had OSA as well as hypertension and at least one other cardiovascular disease risk factor, to use either CPAP or an oral appliance when sleeping for six months. The devices used technology to measure adherence. 

The primary outcome was change in 24-hour blood pressure at six months compared with baseline, with MAD non-inferior to CPAP. 

Those in the MAD group recorded a statistically significant reduction in the 24-hour mean arterial blood pressure from baseline (95.6mmHg) to six months (93.5mmHg), whereas there was no significant difference in the CPAP group (95.5mmHg at baseline and 95.3mmHg at six months). 

There were also significant reductions in systolic and diastolic blood pressure in the MAD group, and blood pressure reduction was particularly notable when asleep. 

At six months, residual apnoea hypopnea index was a median 10.8 events per hour in the MAD group, compared with 2.0 in the CPAP group. There was a statistically significant improvement in daytime sleepiness from baseline to six months for both groups, with no difference between the two groups. 

The American Academy of Sleep Medicine recommends using OSA devices for four or more hours on at least 70% of nights, and both groups were close to meeting this recommendation (69% of the MAD group and 64% of the CPAP group).  

However, the more than half the MAD group used it for at least six hours per night compared with less than a quarter of the CPAP group, leading the authors to suggest that the difference in blood pressure improvement could come down to adherence. 

“The MAD patients simply used the device longer,” said study author Professor Ronald Lee Chi-Hang of the National University of Singapore in a statement.  

“That also might explain why the blood pressure reduction at nighttime, when the patients are actually using it, had a better reduction in the MAD arm.” 

There were several limitations of the study. Firstly, it was conducted during the covid pandemic, when most participants stayed and slept at home, potentially resulting in increased adherence. The patients in the study had well-controlled blood pressure and most did not suffer from excessive daytime sleepiness, so the results may not be generalisable to other OSA patients.  

Finally, the authors pointed out that all the participants were of Chinese ethnicity, although they said there was no biological reason why the results couldn’t be generalised to Caucasian populations.  

“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 Professor Chi-Hang. 

“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.” 

Journal of the American College of Cardiology 2024, online 6 April 

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