Lifestyle Modification Program to Treat Obstructive Sleep Apnea Patients (OSA)

• Change in Apnea-hypopnea Index (AHI) [ Time Frame: baseline and 1 year ] [ Designated as safety issue: No ]
  AHI is a count of the number of upper airway obstruction per hour of sleep. The index will be derived from the overnight home sleep study.
  
  

• Epworth Sleepiness Score (ESS) [ Time Frame: baseline and 1 year ] [ Designated as safety issue: No ]
  The Epworth Sleepiness Scale (ESS) is a questionnaire for assessing daytime sleepiness. It was first described in 1991 as a simple, self-administered questionnaire. The questionnaire is based on eight common situations in life. Subjects are asked to rate on a scale of 0-3 about how likely they would fall asleep or doze off in these circumstances. This gives a total score of 0 to 24 in each subject.
  
  
• SF 36 questionnaire [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  The Short Form Health Survey (SF-36) is a survey of patient health. It is commonly used in health economics as a variable in the quality-adjusted life year calculation to determine the cost-effectiveness of a health treatment. It consists of eight scaled scores, which are the weighted sums of the questions in their section. The eight sections are: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health.
  
  
• biochemical profile [ Time Frame: baseline and 1 year ] [ Designated as safety issue: No ]
  Measurement of the lipid profile, fasting glucose will be performed in baseline and 1 year.
  
  

Obstructive sleep apnea syndrome (OSAS) is a common form of sleep-disordered breathing (SDB) characterized by repetitive episodes of cessation of breathing during sleep due to upper airway collapse. It causes sleep fragmentation, disabling daytime sleepiness, impaired cognitive function and poor quality of life. In addition, OSAS is associated with non-fatal and fatal cardiovascular consequences including sudden death, in addition to an increased risk of road traffic accidents.

OSAS is equally common among the middle-aged male Caucasian and Hong Kong (HK) Chinese populations with prevalence rates of at least 4%. The prevalence and severity of OSAS tend to increase through adult life, peaking in the late fifties to mid sixties, after which it fails to increase or decrease. Another group of investigators reported high prevalence rates of SDB in a group aged 65-95 years of 70% for men and 56% for women, at least double those reported for middle-aged cohorts.

Risk factors for OSA include obesity, increasing age, being male, abnormal craniofacial morphology, nasal obstruction, genetic factors. OSA is associated with several cardiovascular consequences and social consequences e.g. motor vehicle accidents, impaired cognitive performance, depression. Various epidemiologic studies have shown an association between OSA and hypertension. In cross-sectional study, OSA was associated with increased prevalence of self-reported heart failure and stroke. OSA has been shown to be independently associated with coronary artery disease after adjustment for traditionally considered risk factors.

Continuous positive airway pressure (CPAP) is considered as the first-line treatment for OSA. Oral appliance has been shown to reduce the severity of sleep disordered breathing and leads to symptomatic improvement especially in mild to moderate OSA. The compliance with CPAP is low particularly in mild or moderate OSA patients and it is not a curative treatment of OSA. It has to be used in every night on a regular basis. Weight reduction has always been advocated in patients with OSA who are overweight and may lead to improvement in the severity of OSA. A population-based longitudinal study showed that a 10% weight loss predicted a 26% decrease in apnoea-hypopnoea index (AHI), a count of the number of upper airway obstructions per hour of sleep.

The existing studies about weight loss are limited by small sample size, short duration (<6 months), focus on very low calorie diet program or surgically induced weight loss program only. However, none of them have applied lifestyle modification program (LMP) which emphasizes on long term lifestyle and behavior change. Therefore, the investigators plan to conduct a randomized controlled trial among Chinese OSA patients by comparing the efficacy of LMP against usual clinical lifestyle advice alone on the improvement of OSA symptoms.

Aim of the study:

The investigators aim to test the hypothesis that LMP is superior to lifestyle advice alone in the management of Chinese patients with OSA. The primary outcome measure is the change of AHI. The secondary outcome measures are changes in quality of life, symptoms related to OSA, glucose, and insulin metabolism parameters.

Hypothesis:

The investigators hypothesize that more OSA patients in a low glycemic index dietary intervention program than patients receiving simple lifestyle advice alone will have reduction in AHI.