Data extraction and synthesis: Trial quality was assessed and two reviewers extracted data independently. Study authors were contacted for missing information.
Results: Twelve trials were included, involving 509 participants. All the studies had some methodological shortcomings. Overall, OA use improved the apnoea–hypopnoea index (AHI) more than inactive control. The AHI for the former was -13.17 (95% confidence interval (CI), -18.53 to -7.80) in parallel group data from four studies. Use of an OA reduced daytime sleepiness in two trials, giving a weighted mean difference (WMD) of -1.77 (95% CI, -2.91 to -0.62). OA use was less effective than continuous positive pressure in reducing the AHI (respectively giving a WMD of 13 (95% CI, 7.63-18.36) in parallel studies from two trials and of 6.75 (95% CI, 4.93-8.57) in crossover studies from six trials). No significant difference was observed on symptom scores (data from three trials), however.
Nasal continuous positive airway pressure (nCPAP) was more effective at improving minimum arterial oxygen saturation during sleep compared with OA use. In two small crossover studies, participants preferred OA therapy to nCPAP.
Conclusions: There is limited evidence that suggests OA use improves subjective sleepiness and sleep-disordered breathing compared with control. nCPAP is apparently more effective in improving sleep-disordered breathing than OA use. Until there is more definitive evidence on the effectiveness of OA, it is probably appropriate to restrict OA therapy to patients who have sleep apnoea but are unwilling or unable to comply with nCPAP therapy.
.
