STAGE II: This stage was comprised of the multicenter, randomized, parallel group, comparative effectiveness trial to compare positive airway pressure (PAP) vs. oral appliance (OA) therapy in improving hypertension and abnormalities in cardiovascular function in overweight/obese patients with obstructive sleep apnea (OSA). Data collected during the STAGE II study were incorporated in Part 3 of the STAGE I study. This comparative effectiveness trial was conducted at 4 clinical centers, and the data collected during this trial were used to test the electronic network informatics infrastructure. The primary aim of the Stage II CET was to evaluate and compare the effect of positive airway pressure and oral appliance therapy on 24-hour blood pressure and vascular structure and function associated with obstructive sleep apnea in a primarily female, overweight/obese hypertensive population.