Impact of CPAP on Functional Outcomes in Milder OSA

描述（由申请人提供）：阻塞性睡眠呼吸暂停（OSA）根据美国睡眠医学学会（American Academy of sleep Medicine）定义的每小时睡眠呼吸障碍（RDI）的数量分为轻度、中度或重度。持续气道正压通气（CPAP）是治疗睡眠呼吸暂停的主要方法。当使用该装置时，该装置向上呼吸道输送的压力柱立即消除了呼吸障碍。随机对照研究的证据表明，CPAP还能改善严重OSI患者（即RDI患者）的功能状态，以及OSA的关键表现——白天过度嗜睡。然而，对于轻度OSA患者，即轻度（RDI 5-15）或中度（RDI 16-30） OSA患者功能状态的改善研究有限。在与OSA相关的功能结局的对照研究中已经报道了巨大的安慰剂效应，这就要求在评估这种治疗的真正影响的调查中需要安慰剂。三项针对轻度阻塞性睡眠呼吸暂停的随机对照研究的结果都是模棱两可的，主要是由于严重的方法学局限性。目前尚不清楚CPAP治疗是否能改善病情较轻患者的日常功能（RDI 5-30）。这是一个关键问题，因为这种疾病严重程度代表了OSA的最大部分，占美国人口的15%。使用Granger功能评估模型，我们的主要目的是确定CPAP治疗后轻度OSA患者的功能状态是否得到改善。我们将采用随机安慰剂对照平行组设计，在表现出明显白天嗜睡的大样本中使用假cpap装置作为安慰剂。我们将检验一个假设，即在治疗8周后，与假CPAP相比，主动CPAP治疗患者的功能状态变化（通过睡眠功能结果问卷测量）更大。本研究的次要目的是：1)检验CPAP是否也能改善白天嗜睡；2)确定CPAP是否可以降低夜间血压，从而降低与OSA相关的卒中和高血压的风险。

DESCRIPTION (provided by applicant): Obstructive sleep apnea (OSA) is characterized as mild, moderate, or severe according to the number of respiratory disturbances per hour of sleep (RDI) as defined by the American Academy of Sleep Medicine. Continuous positive airway pressure (CPAP) is the primary treatment for sleep apnea. The column of pressure delivered to the upper airway by this device immediately eliminates the respiratory disturbances when it is applied. There is evidence from randomized controlled studies that CPAP also improves functional status, and the key manifestation of OSA, excessive daytime sleepiness, in individuals with severe OSI, i.e., RDI >30. However, there has been limited work exploring improvement in functional status in patients with less severe OSA, i.e., those with mild (RDI 5-15) or moderate (RDI 16-30) disease. The large placebo effect that has been reported in controlled studies of functional outcomes associated with OSA mandates the need for a placebo in investigations evaluating the true impact of this treatment. Results from the three randomized controlled studies in milder OSA that have examined this issue have been equivocal principally because of serious methodological limitations. It remains unclear whether CPAP treatment improves daily functioning in those with milder disease (RDI 5-30). This is a critical issue as this level of disease severity represents the largest segment of OSA and comprises 15% of the US population. Using Granger's model of functional assessment our primary aim is to determine whether functional status improves in patients with milder OSA following CPAP treatment. We will employ a randomized placebo-controlled parallel groups design using a sham-CPAP device as the placebo in a large sample manifesting significant daytime sleepiness. We will test the hypothesis that the change in functional status (measured by the Functional Outcomes of Sleep Questionnaire) after 8 weeks of treatment will be greater for patients treated with active CPAP compared to sham CPAP. Secondary aims of the study are: 1) to examine whether CPAP also improves daytime sleepiness; 2) to determine whether CPAP can reduce nocturnal blood pressure to lower the risk for stroke and hypertension linked to OSA.