Obstructive sleep apnea (OSA) is a prevalent public health issue with an attributable risk of cardio- and cerebrovascular morbidity and mortality. Furthermore, OSA is related to a high socioeconomic burden due to its clinical daytime consequences such as excessive daytime sleepiness, impaired cognitive performance and reduced quality of life. Oral appliances that protrude the mandible, the mandibular advancement devices (MAD), significantly reduce OSA severity in the majority of patients. However, in a third of patients, the efficacy is not medically appropriate to reduce the long-term consequences of OSA. Furthermore, the efficacy of MAD therapy is inconsistent among patients. Therefore, a high need exists for upfront prediction of treatment outcome in the individual OSA patient. There is no validated method that can achieve upfront selection of candidates for MAD therapy in an accurate and reliable way. Nowadays, it is increasingly recognized that OSA is a multifactorial disease. In the proposed research project, a prospective prediction model with a combination of different pathophysiological traits will be assessed. Furthermore, up to now, our understanding of MAD therapy relies on relatively small studies lacking power. Therefore, we will evaluate this predictive model, as well as the long-term effectiveness, morbidity and mortality in a large international cohort of patients treated with MAD.