PURPOSE OF REVIEW:
Obstructive sleep apnea (OSA) is heterogeneous in terms of contributing pathophysiological mechanisms, clinical presentation, and consequences. Different study models from animal models of intermittent hypoxia over case-control, cohort, and population-based observational studies to uncontrolled interventional and randomized controlled interventional trials have contributed to the knowledge base. Controversial findings on underlying mechanisms and consequences of untreated OSA have challenged the field and resulted in uncertainty in treatment recommendations.
The heterogeneity of OSA in pathogenesis and clinical outcomes and strengths and limitations of different study models and designs used for studying OSA pathophysiology and cardiovascular consequences are discussed on the background of controversial findings on cardiovascular outcomes in OSA. In addition, recent findings from randomized controlled continuous positive airway pressure therapy withdrawal trials, an efficient and controlled study model, are highlighted.
Novel designs for clinical trials on long-term outcomes in the highly prevalent patient group with OSA addressing the heterogeneity in underlying mechanisms, different phenotypes in terms of cardiovascular risk, and new treatment concepts are needed to improve clinical practice standards.