Long-term Effects of CPAP on Lipidemia and Hs-CRP Levels in OSA Patients
Condition: Obstructive Sleep Apnea; Coronary Heart Disease
MeSH terms: Apnea; Sleep Apnea Syndromes; Sleep Apnea, Obstructive; Heart Diseases; Coronary Disease; Coronary Artery Disease; Myocardial Ischemia; Hyperlipidemias
Study type: Interventional

Summary: 
      The increased risk of atherosclerotic morbidity and mortality in patients with obstructive
      sleep apnea (OSA) has been linked to hypertension, insulin resistance, dyslipidemia, and
      systemic inflammation. The relationship regarding obstructive sleep apnea (OSA) and lipidemia
      and systemic inflammation is far from conclusion for obesity as a strong confounding factor.
    

Detailed description: 
      Obstructive sleep apnea (OSA) is a common sleep disorder characterized by recurrent episodes
      of partial or complete obstruction of the upper airway during sleep, resulting in sleep
      fragmentation and oxyhemoglobin desaturation. OSA is recognized as an important public health
      problem in developed country, affecting 9 and 24% of middle-aged females and males,
      respectively. OSA, however, is not recognized as an abnormality for the majority and doesn't
      get more attention from most people in China. Increasing evidence now indicates that severe
      OSA is associated with increased cardiovascular morbidity and mortality, mainly due to acute
      myocardial infarction and stroke. Atherosclerosis is a key mechanism for these cardiovascular
      events. Numerous studies have explored the relationship between hypertension and OSA. And
      these studies confirms that OSA is an important identifiable cause of hypertension and a
      raised blood pressure has been shown to fall with effective continuous positive airway
      pressure (CPAP) treatment. Dyslipidemia, an established independent risk factor for coronary
      heart disease (CHD) and atherosclerosis, is common in patients with OSA. But there are
      limited interventional data on OSA and lipidemia, showing controversial results. Several
      studies9,10 have shown a direct relationship between OSA and lipid profiles, independently of
      obesity, while other studies have demonstrated that obesity, as a confounding factor,
      contributed to dyslipidemia among OSA patients.11,12 Taken together, adiposity is a strong
      confounding factor for interpretation of the causal relationship between dyslipidemia and
      OSA. Few studies have focused on nonobese patients.10,13 There are only a small number of
      randomized trials that have examined the effect of CPAP on fasting lipid profiles14,15 and
      none were specifically designed to evaluate the lipid profiles. Furthermore, most studies
      assessed the impact of CPAP on OSA-related lipids without statin therapy. In this way, it may
      be useful to avoid the disturb conditions due to statin treatment. But it is impractical to
      those patients with OSA and CHD. Since statins, in addition to decreasing hyperlipidemia
      levels, also inhibit inflammatory cytokines and play a critical role of plaque stabilization
      in CHD patients. Similarly, the condition existed in the examination of high-sensitivity
      C-reactive protein (hs-CRP) in CHD subjects with OSA. Therefore, the aims of the present
      study were (1) to establish whether CPAP therapy decreases lipid profiles and hs-CRP levels
      in nonobese patients with CHD and OSA, (2) to establish whether a relationship exists between
      the severity of OSA and levels of these circulating markers, and (3) to demonstrate a
      possible mechanism for the prevention of cardiovascular disease.
    

Intervention name(s): Continuous Positive Airway Pressure Ventilator
Intervention type(s): Device
Intervention description(s): CPAP group received fixed-level CPAP titration using an automated pressure setting device for one night. The optimal CPAP pressure for each patient in the CPAP group was set at the minimum pressure required to abolish snoring, obstructive respiratory events, and airflow limitation for 95% of the night, according to a previous validation by our study.
Other intervention name(s): Continuous Positive Airway Pressure(CPAP)
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Investigator)
Primary purpose: Treatment
Keywords: obstructive sleep apnea; coronary heart disease; continuous positive airway pressure; lipid profiles; high-sensitivity C-reactive protein