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Dayton Dental Sleep Medicine 2014 Newsletter:

Australian Study Indicates That MADs Compare Favorably with CPAP

A study published in the American Journal of Respiratory and Critical Care Medicine reports on a direct comparison between CPAP therapy and oral
appliance therapy utilizing Mandibular Advancement Devices (MAD). The study, which was conducted at the Department of Respiratory Sleep Medicine at the Royal North Slope Hospital, St. Leonards, Australia, utilized a randomized crossover trial to compare the effects of one month each of CPAP and MAD treatment for patients with moderate-severe OSA. This represents the largest such study to date.

Metrics for comparison of the two therapies included both cardiovascular and neuro-behavioral outcomes. Among these were 24-hour blood pressure and arterial stiffness, along with subjective sleepiness, driving simulator performance and quality of life evaluations.

A total of 135 patients with moderate-sever sleep apnea (AHI of 25 +/-12) were assigned to a treatment order. Of these, some 108 completed the trial period with both devices. Results showed that CPAP therapy was more efficacious in reducing AHI as compared to MAD therapy. CPAP provided an average AHI reduction to 4.5 (=/- 6.6), while MAD therapy showed an average AHI reduction to 11.1 (+/- 12).

During treatment, reductions in arterial stiffness of between 1 and 2 percent was recorded, based on the aortic augmentation index, and these results were similar for both therapies. Neither MAD or CPAP therapy provided a significant reduction in baseline blood pressure measurements for the overall study group but within the subset of patients who were initially hypertensive, both therapies provided a roughly equivalent reduction in BP of between 2 and 4 mm Hg.

More significant changes were recorded from the neuro-behavioral metrics. According to the authors: "Overall, this study found that improvements with MAD in sleepiness, quality of life and driving simulator performance were as good or better than CPAP. Previous studies that have compared subjective sleepiness and quality of life after treatment with CPAP and oral appliances have either favored CPAP or have shown similar effectiveness between treatments. However, in the studies that favored CPAP, non-adjustable oral appliances were used and these may have been inferior to full adjustable models, as used in our study.

Use MAD Therapy for Severe OSA?

Should the guidelines regarding the use of MAD therapy for severe OSA be changed? This question was raised in a commentary authored by Drs.
David White and Shirin Shafazand in the Journal of Clinical Sleep Medicine.

The authors note that current guidelines from the American Academy of Sleep Medicine suggest that Mandibular Advancement Devices (MAD) should be used primarily for treatment of patients who exhibit mild to moderate OSA symptoms. The authors question these guidelines, based on their assessment of data provided by a study conducted at the Royal North Shore Hospital, St. Leonards, Australia, which involved comparative assessments of CPAP and MAD therapy.

Of the OSA patients participating in the study, 32 percent were classified as "severe" (AHI > 30). The mean AHI for this group was 42 prior to therapy, and 18-19 when using MAD therapy.

By further breaking down this data, the authors concluded that: 7 patients had a treated AHI > 30; 13 had an AHI > 20; 8 had an AHI of 10-20 and 12 had an AHI > 10.

Based on this analysis of the data, the authors concluded that while not all severe OSA patients respond well to MAD, a sizable minority does showmarked improvement of symptoms. The authors also note that study patients showed a similar improvement in sleepiness based on the Epworth Sleepiness Scale with MAD as they did on CPAP.

In light of this information, the authors state that "the conclusion that MAD is not an appropriate conclusion for patients with severe OSA may be incorrect."

They go on to add that "Although MADs may not be the first-line therapy for patients with severe OSA, the take-home message here is simply that a follow-up sleep study is probably needed for severe OSA patients to assess efficacy; not that MAD is not a good choice for these patients."

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