Effect of Weight Loss and CPAP on OSA and Metabolic Profile Stratified by Craniofacial Phenotype
Condition: Obstructive Sleep Apnea
MeSH terms: Sleep Apnea, Obstructive; Weight Loss
Study type: Interventional

Summary: 
      Obstructive sleep apnea (OSA) is a common form of sleep-disordered breathing (SDB). Weight
      reduction has always been advocated in patients with OSA who are overweight and may lead to
      improvement in the severity of OSA. Previous study reported a randomized controlled trial of
      dietician-led lifestyle modification program (LMP) in 104 patients and found that LMP group
      had significantly more weight loss and reduced OSA severity, and the response was sustained
      after 8 months.

      This study is aimed to compare the effect of weight loss or CPAP alone on subclinical
      inflammation, insulin resistance and blood pressure in patients with obesity and
      moderate-to-severe obstructive sleep apnea, stratified according to the degree of
      craniofacial restriction.

      The study plans to recruit consecutive patients who have been referred to the Respiratory
      Clinic at the Prince of Wales Hospital with clinical suspicion of sleep-disordered breathing
      with specific study entry criteria including an age of 18 or more, body mass index (BMI) >25
      kg/m2, and moderate to severe OSA diagnosed by home sleep study. Patients having conditions
      that will affect the serum level of hsCRP will be excluded.
    

Detailed description: 
      Obstructive sleep apnea (OSA) is a common form of sleep-disordered breathing (SDB). It causes
      sleep fragmentation, disabling daytime sleepiness, impaired cognitive function, poor quality
      of life and cardiovascular diseases. Weight reduction has always been advocated in patients
      with OSA who are overweight and may lead to improvement in the severity of OSA. Previous
      study reported a randomized controlled trial of dietician-led lifestyle modification program
      (LMP) in 104 patients and found that LMP group had significantly more weight loss and reduced
      OSA severity, and the response was sustained after 8 months. However, a wide variety of
      response to the therapy was observed with 21.3% of patients with severe disease that
      converted to mild to moderate and only 6.6% of those with severe disease who became mild in
      severity. Apart from obesity, craniofacial factors are well recognized in the pathogenesis of
      OSA and are likely to play an important role in influencing the response to weight loss. For
      the same degree of OSA severity, Caucasians were more overweight whereas Chinese exhibited
      more craniofacial bony restriction. Recent studies showed that a smaller craniofacial
      skeleton is associated with better response from weight loss program in terms of OSA
      improvement. With vast majority of studies investigating the cardiometabolic changes after
      CPAP or weight loss on patients with OSA, evaluation based on craniofacial restriction, the
      key factor in the pathogenesis, is lacking.

      This study aimed to compare the effect of weight loss or CPAP alone on subclinical
      inflammation, insulin resistance and blood pressure in patients with obesity and
      moderate-to-severe obstructive sleep apnea, stratified according to the degree of
      craniofacial restriction.

      The study plans to recruit consecutive patients who have been referred to the Respiratory
      Clinic at the Prince of Wales Hospital with clinical suspicion of sleep-disordered breathing
      with specific study entry criteria including an age of 18 or more, body mass index (BMI) >25
      kg/m2, and moderate to severe OSA diagnosed by home sleep study. Patients having conditions
      that will affect the serum level of hsCRP will be excluded.
    

Intervention name(s): Lifestyle modification; Continuous positive airway pressure (CPAP)
Intervention type(s): Behavioral; Device
Intervention description(s): A caloric reduction of 10-20% in daily energy intake from the patient's usual diet (i.e. a deficit ≥ 200 calories per day) will be set as the general initial goal, which will be adjusted subsequently based on changes in body weight with target body mass index (BMI) towards 23 kg/m2.; Patients randomized into the continuous positive airway pressure (CPAP) group in each arm will be interviewed by the physician on duty and invited to start autoCPAP treatment for 6 months. They will be offered a CPAP education package. Patients will then commence autoCPAP treatment for 6 months at home.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment