The Effects of Treating Obese and Lean Patients With Sleep Apnea
Condition: Sleep Apnea; Obesity
MeSH terms: Apnea; Sleep Apnea Syndromes
Study type: Interventional

Summary: 
      The investigators' overall goal is to compare the effect of CPAP treatment on intermediate
      cardiovascular risk measures in obese versus lean patients with obstructive sleep apnea
      (OSA). The overall hypothesis is that, adjusting for OSA severity and obtaining normative
      data from non-OSA subjects with comparable amounts of visceral adiposity, the two OSA groups
      will have comparable improvements in daytime sleepiness, but that the cardiovascular and
      metabolic improvements following CPAP therapy will be decreased in OSA patients with
      increased visceral adipose tissue. The investigators anticipate that, although there will be
      a greater absolute change in markers of sympathetic activity, inflammation and oxidative
      stress in obese compared to lean OSA patients following CPAP treatment, the levels will still
      be abnormally high in the obese patients resulting in the decreased improvements in insulin
      resistance, arterial blood pressure, and vascular health in obese versus lean OSA patients.
    

Detailed description: 
      Obesity and obstructive sleep apnea (OSA) are independent risk factors for insulin
      resistance, systemic hypertension and cardiovascular disease. Both obesity and OSA are
      associated with increased sympathetic activity, inflammatory activity, and oxidative stress,
      the presumed mediators of their shared clinical consequences. Due to the conflicting results
      of previous intervention studies treating OSA patients with CPAP, the investigators still do
      not know if treatment of obese OSA patients has a substantial benefit on these risk factors.
      In Aim 1, to determine the effects of obesity on the response to CPAP treatment in OSA
      patients, the investigators will compare responses in daytime sleepiness, insulin resistance,
      and arterial blood pressure following CPAP treatment in obese and lean OSA patients,
      stratified by the amount of abdominal visceral adipose tissue, a fat depot associated with
      increased sympathetic activity, inflammation, and oxidative stress, and a more powerful
      predictor than BMI of adverse cardiovascular and metabolic outcomes. Aim 2 will determine the
      effect of CPAP treatment in these two patients groups on sympathetic activity, and
      inflammatory and oxidative stress biomarkers. The overall hypothesis is that, adjusting for
      OSA severity and obtaining normative data from non-OSA subjects with comparable amounts of
      visceral adiposity (Aim 3), the two OSA groups will have comparable improvements in daytime
      sleepiness, but that the cardiovascular and metabolic improvements following CPAP therapy
      will be decreased in OSA patients with increased visceral adipose tissue. The investigators
      anticipate that, although there will be a greater absolute change in markers of sympathetic
      activity, inflammation and oxidative stress in obese compared to lean OSA patients following
      CPAP treatment, the levels will still be abnormally high in the obese patients resulting in
      the decreased improvements in insulin resistance, arterial blood pressure, and vascular
      health in obese versus lean OSA patients. Relevance: Obese patients are at increased risk of
      developing sleep apnea. Both obesity and sleep apnea are felt to increase the risk of
      diabetes, hypertension, and cardiovascular disease. The proposed research will begin to
      determine if treating obese patients with sleep apnea helps to reduce these risks. If the
      beneficial effects of CPAP treatment are reduced in obese compared to lean patients with
      sleep apnea, then treatment of sleep apnea in obese patients needs to be combined with
      effective management of their obesity.
    

Intervention name(s): Positive Airway Pressure During Sleep (ResMed S9 Elite); Usual Care
Intervention type(s): Device; Other
Intervention description(s): Positive airway pressure during sleep (ResMed S9 Elite).; Usual care.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Sleep Apnea; Obesity