Although continuous positive airway pressure (CPAP) has become the standard of care in the treatment of obstructive sleep apnea (OSA), 2 systematic reviews have questioned its utility. Since the publication of these reviews, several randomized controlled trials have been reported. We, therefore, performed a meta-analysis to assess the effect of CPAP on subjective and objective sleepiness.
We conducted a thorough literature search to identify all published randomized controlled trials of CPAP in patients with OSA. Meta-analyses were performed using a random-effects model. Statistical heterogeneity was assessed using the Q statistic.
Twelve trials of CPAP in patients with OSA meeting our inclusion criteria were found. The Epworth Sleepiness Scale score was reported in 11 studies (706 patients). A meta-analysis found that CPAP reduced the Epworth Sleepiness Scale score an average of 2.94 points more than placebo (P<.001). The heterogeneity (Q10 = 57.7, P<.001) between studies could not be explained by differences in sex composition, mean age, mean body mass index, or country of study. Trials recruiting subjects with severe OSA plus sleepiness (mean apnea-hypopnea index, ≥30 events per hour; and mean Epworth Sleepiness Scale score, ≥11) had a greater decrease in the Epworth Sleepiness Scale score than the other studies (4.75 vs 1.10; P<.001). Objective measures of sleepiness were reported in 8 trials (482 subjects). Continuous positive airway pressure increased sleep onset latency by 0.93 minute (P = .04) more than placebo.
Continuous positive airway pressure therapy significantly improves subjective and objective measures of sleepiness in patients with OSA across a diverse range of populations. Patients with more severe apnea and sleepiness seem to benefit the most.