Background Obstructive sleep apnoea (OSA) is associated with increased daytime sleepiness. Previous meta-analyses have shown that both continuous positive airway pressure (CPAP) and mandibular advancement devices (MADs) reduce the Epworth Sleepiness Score (ESS), a common measure of daytime sleep propensity. However, no meta-analysis has yet identified which treatment is superior in reducing ESS, perhaps due to a lack of studies directly investigating the two treatments. In addition, the effect of CPAP usage on ESS has yet to be thoroughly explored.
Methods We searched Medline and the Cochrane Library up to the end of May 2015 to identify randomised controlled trials in OSA investigating the effect of CPAP and/or MADs against each other or an inactive control (IC, placebo or no treatment) on ESS. A network meta-analysis was used to incorporate both direct and indirect evidence to estimate the difference between the three treatment groups on ESS. Meta-regression was used to assess the influence of CPAP usage and average baseline patient characteristics on the effect of CPAP compared to ICs.
Findings A total of 67 studies comprising 6873 patients were included in the meta-analysis. Of these, 51 (5898 patients) assessed CPAP against an IC. CPAP and MADs were estimated to reduce ESS by 2.5 (95% CI 2.1,2.9) and 1.7 (95% CI 1.1,2.3) points respectively compared to an IC. CPAP was estimated to reduce the ESS by a further 0.8 points compared to MADs (95% CI 0.1,1.4; p = 0.015). However, there was some suggestion of publication bias in favour of CPAP which may have inflated this effect. There was no evidence that studies reporting higher CPAP usage also reported larger treatment effects.
Interpretation Both CPAP and MADs are effective treatments for reducing daytime sleepiness in patients with OSA. CPAP appears to be the most effective treatment and should be recommended for more severe or sleepier OSA patients. However, MADs are a suitable second-line treatment should CPAP not be tolerated.