A Randomized Controlled Trial of Continuous Positive Airway Pressure in Mild Obstructive Sleep Apnea

Abstract

A common clinical dilemma faced by sleep physicians is in deciding the level of severity at which patients with obstructive sleep apnea (OSA) should be treated. There is particular uncertainty about the need for, and the effectiveness of, treatment in mild cases. To help define the role of nasal continuous positive airway pressure (CPAP) treatment in mild OSA we undertook a randomized controlled cross-over trial of CPAP in patients with an apnea- hypopnea index (AHI) of 5 - 30 (mean, 12.9 +/- 6.3 SD). Twenty-four-hour blood pressure and neurobehavioral function were measured at baseline, after 8 wk of treatment with CPAP, and after 8 wk of treatment with an oral placebo tablet. Twenty-eight of 42 patients enrolled in the study completed both treatment arms. Baseline characteristics were not different between those who completed the study and those who did not complete the study. Patients used CPAP for a mean (SD) of 3.53 (2.13) h per night and the mean AHI on the night of CPAP implementation was 4.24 (2.9). Nasal CPAP improved self-reported symptoms of OSA, including snoring, restless sleep, daytime sleepiness, and irritability (in-house questionnaire), more than did placebo, but did not improve objective (Multiple Sleep Latency Test) or subjective (Epworth Sleepiness Scale) measures of daytime sleepiness. We found no benefit of CPAP over placebo in any tests of neurobehavioral function, generic SF-36 (36-item Short Form Medical Outcomes Survey) or sleep-specific (Functional Outcomes of Sleep Questionnaire) quality of life questionnaires, mood score (Profile of Moods States and Beck Depression Index), or 24-h blood pressure. However, the placebo tablet resulted in a significant improvement in a wide range of functional variables compared with baseline. This placebo effect may account for some of the treatment responses to CPAP observed previously in patients with mild OSA.

Sleep Apnea and Cardiovascular Disease

“…150 In addition, short-term CPAP treatment in patients with well-controlled hypertension did not elicit any BP improvement. 151 Recent studies have more often been placebo controlled, [152][153][154] comparing CPAP with either placebo pills or with sham CPAP. BP reduction is either modest or absent in normotensive subjects but may be more evident in hypertensives.…”

The contribution of fatigue and sleepiness to depression in patients attending the sleep laboratory for evaluation of obstructive sleep apnea

“…Similarly, Bardwell et al (2003) found that depressive symptoms accounted for approximately 40% of the variance in fatigue reported in OSA patients after apnoea severity was taken into account [25]. In addition to these findings, levels of both depressive symptoms and fatigue have been found to be attenuated by CPAP treatment [36][37], further supporting the existence of an interaction between these symptoms within sleep disturbed populations.…”

Eight Hours of Nightly Continuous Positive Airway Pressure Treatment of Obstructive Sleep Apnea Improves Glucose Metabolism in Patients with Prediabetes. A Randomized Controlled Trial

“…Although oral placebo has been used as a control group in several randomized controlled CPAP trials (49)(50)(51)(52)(53)(54)(55), an alternative, commonly used approach is sham-CPAP, a specially designed CPAP device with minimal and clinically ineffective airway pressure. We chose to use oral placebo rather than sham-CPAP in the control group for several reasons.…”