Effectiveness of different mandibular advancement device designs in obstructive sleep apnoea therapy: A systematic review of randomised controlled trials with meta-analysis.

Mandibular advancement devices (MADs) are used to treat patients with obstructive sleep apnoea (OSA). To date, there are no data that identify the most effective MAD design for apnoea-hypopnea index (AHI) reduction. The purpose of this systematic review is to investigate the effectiveness of different MAD designs in AHI reduction and oxygen saturation improvement in OSA patients. An electronic search was performed in MEDLINE, Cochrane Database, Scopus, Web of Knowledge and LILACS. Randomised controlled trials (RCTs) investigating the reduction of AHI on adult patients wearing MAD for OSA were included. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the risk of bias by the Cochrane Collaboration's tool for assessing risk of bias in randomised controlled trial. The success rate of each study was computed: [(mean baseline AHI - mean AHI after treatment)/mean baseline AHI]. Fifty RCTs were included. The risk of bias resulted with some concerns in most of the studies. The GRADE scores indicated that the quality of evidence was very low. The meta-analysis showed a success rate with mono-bloc and duo-bloc MADs respectively of 0.821 [0.722-0.887] and 0.547 [0.443-0.637]. The mono-bloc compared with duo-bloc better improved the minimum oxygen saturation (10.048 [7.733-12.363] and 3.357 [2.290-4.423], respectively). There is a very low quality body of evidence that mono-bloc MADs are more effective in reducing AHI and improving minimum oxygen saturation compared with duo-bloc MADs. The study protocol was registered on PROSPERO (n. CRD42019118084).