A Cochrane review [Abstract] 1 included 4 studies with a total of 132 subjects. Two studies compared nasal mask with the Oracle oral mask and showed no significant difference in compliance at one month (mean difference 0.17 hours per night, 95% CI -0.54 to 0.87). There were also no significant differences in any of the physiological parameters, Epworth Sleepiness Scale (ESS), or symptoms. A single study comparing nasal mask with nasal pillows showed a significant difference in compliance in favour of nasal pillows (percentage of days used; nasal pillows 94.1±8.3%; nasal mask 85.7±23.5%, P=0.02). Nasal pillows were also associated with fewer overall adverse effects and greater interface satisfaction. One study comparing nasal mask with face mask showed that compliance was significantly greater with use of a nasal mask (mean difference 1.0 hour per night, 95% CI 0.3 to 1.8). Nasal mask was also associated with significantly lower ESS scores and was the preferred interface in almost all patients.
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison) and by indirectness (participants with severe obstructive sleep apnoea only; different interface options for CPAP not examined).
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