The effect of Oral Appliance Therapy (OAT) for Obstructive Sleep Apnoea (OSA) on markers of cardiovascular risk

INTERVENTION: Oral Appliance Therapy (OAT) for Obstructive Sleep Apnoea OAT is a recommended therapy for OSA. The therapy entails wearing a customised dental device during sleep. The device is digitally milled from dental impressions obtained by a dentist, and hence each device is customised to an individual's dentition. In this trial OAT will be implemented by a dentist with previous experience in OAT. OAT will be monitored by the treating dentist throughout the trial. Participants will attend an initial dental visit to obtain impressions to manufacture the device ( 1 hour). The device will be fitted by the dentist at a second visit ( 40 minutes). Participants will be instructed to wear the device whenever they sleep for the duration of the trial (6 months). Participants will have follow‐up dental visits at mid‐point (3 months) and end of the trial (6 months, 30 minutes per visit). Participants will have opportunity for additional dental visits on an ad hoc basis if there are any issues which require assessment by the dentist, such as issues with device fit. All devices are fitted with an objective compliance monitor, a small temperature‐sensing chip which is embedded within the appliance material. Compliance data will be downloaded from the chip using a reading station at study visits. CONDITION: Cardiovascular ‐ Coronary heart disease Obstructive Sleep Apnoea;Cardiovascular Disease; ; Obstructive Sleep Apnoea ; Cardiovascular Disease Respiratory ‐ Sleep apnoea PRIMARY OUTCOME: change in 24 hour blood pressure (peripheral and central measured by Oscar 2 ambulatory blood pressure monitor with SphygmoCor)[3 and 6 (primary endpoint) months post intervention commencement] change in arterial stiffness (pulse wave velocity)[3 and 6 (primary endpoint) months post intervention commencement] change in endothelial function (flow mediated dilation of brachial artery by ultrasound)[3 and 6 (primary endpoint) months post intervention commencement] INCLUSION CRITERIA: Obstructive Sleep Apnoea (with ODI(4%) > 15 events/hour) Framingham risk score >15% BMI < 35 kgm2 SECONDARY OUTCOME: Adherence to therapy (data download from sensor chip in appliance)[Daily usage over 6 month intervention period] change in autonomic function (baroreceptor reflex function, Human Non‐Invasive Blood Pressure System, NIBP)[3 and 6 months post intervention commencement] change in autonomic function (blood pressure variability, Human Non‐Invasive Blood Pressure System, NIBP )[3 and 6 months post intervention commencement] change in autonomic function (heart rate variability, ECG)[3 and 6 months post intervention commencement] change in carotid intima media thickness (ultrasound)[3 and 6 months post intervention commencement] Change in disease‐related quality of life (Functional Outcomes of Sleep Questionnaire)[3 and 6 months post intervention commencement] Change in health related quality of life (SF‐36 questionnaire)[3 and 6 months post intervention commencement] Change in subjective daytime sleepiness (Epworth Sleepiness Score)[3 and 6 months post intervention commencement] OAT efficacy, change in oxygen saturation assessed by home oximtery[6 months post intervention commencement] OAT efficacy, change in sleep apnea events as assessed by overnight polysomnography[6 months post intervention commencement]