Obstructive Sleep Apnea and Behavioural Obesity Management in Adult Patients

Abstract

The association between obstructive sleep apnea (OSA) and obesity is well established and their frequent coexistence induces cardio-metabolic impairment. While mechanical therapies such as continuous positive airway pressure (CPAP) offer symptomatic alleviation, they fail to cure OSA in the absence of treatment use. Potential disease resolution depends on obesity reduction however there is a paucity of data regarding intensive weight loss regimes such as a very low energy diet (VLED) and dietary strategies for long-term weight loss maintenance in patients suffering OSA. This thesis entails a lifestyle modification program tailored to patients with OSA to promote behavioural change. An open label cohort study tested this program in 24 patients using mechanical treatment (CPAP or mandibular advancement splint) and in 18 patients not prescribed mechanical treatment. All patients initiated a 2 month VLED and significantly reduced anthropometry and maintained this by 12 month follow up. Healthy cardio-metabolic function was sustained and use of antihypertensive medication was reduced. This model of weight loss was feasible, tolerable and efficacious in a clinical setting. Weight loss maintenance was simultaneously tested in a randomised controlled trial. Stratified patients were allocated to the Australian Guide to Healthy Eating diet (n= 20) or an iso-caloric low glycemic index high protein diet (n= 22) following successful completion of the VLED. Both diets maintained significant obesity reduction and healthy cardio-metabolic function for 10 months. Sympathetic activity measured by the urinary catecholamines epinephrine and norepinephrine and heart rate variability were assessed had no association with weight loss and cannot predict treatment responders. This research provides novel insight into weight loss treatment strategies for patients with OSA in a clinical setting and furthers our understanding of effective obesity management in this vulnerable population.