A Closer Look at the Effect of Oral Appliance Therapy on Blood Pressure in Sleep Apnea

2021 Focused Projects Grant for Junior Investigators

Daniel Vena, PhD
Brigham and Women’s Hospital and Harvard Medical School

Key Project Outcome

The funded project made two key findings:

First, we identified that treatment efficacy as determined by reduction in hypoxic burden, better explains improvements in blood pressure with oral appliance therapy, compared to traditional measure of obstructive sleep apnea (OSA) severity—apnea hypopnea index (AHI), which counts the number of respiratory events per hour of sleep. For example, one SD reduction in hypoxic burden was associated with ~9 mmHg systolic blood pressure reductions, whereas one SD reduction in AHI was associated with only ~4 mmHg blood pressure reduction. This research adds to accumulating evidence that OSA severity measured by hypoxic burden is more tightly linked to adverse cardiovascular outcomes and thus a better metric of OSA severity. As such, while more research is needed, the field needs to begin thinking about moving past the AHI as the de facto OSA severity metric and instead use more physiology-driven metrics, such as the hypoxic burden. Data from this grant will be leveraged to apply for national funding.

Second, we showed that the main factor in producing a blood pressure response with oral appliance therapy is the magnitude of residual disease (i.e., hypoxic burden) with treatment. Therefore, while it may seem as though that oral appliance therapy is not efficacious enough to reduce OSA severity (i.e., hypoxic burden) to a degree that would produce a blood pressure response in the most severe patients, this is not necessarily true. Instead, blood pressure response can occur across any level of disease severity (i.e., low or high risk), but it is conditioned on a sufficient treatment response from OA therapy. This highlights the need for patient selection tools (i.e., endotyping) to appropriately identify patients in whom OA therapy will be efficacious. Patient selection tools combined with better measures of OSA severity will enable the field to identify patients that will respond to non-PAP alternative therapies, such as oral appliances, to a degree that meaningfully reduces risk for adverse outcomes.