Comparison 1. Nasal mask versus Oral mask (Oracle).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Compliance with mask at one month (hours per night)	2		mean difference (Fixed, 95% CI)	0.17 [‐0.54, 0.87]
2 Arousal index (#/hour)	1		#/hour (Fixed, 95% CI)	Totals not selected
3 Apnoea‐hypopnoea index (events/hour)	1		events/hour (Fixed, 95% CI)	Totals not selected
4 Sleep efficiency (%)	1		% (Fixed, 95% CI)	Totals not selected
5 Minimum oxygen saturation (%)	1		% (Fixed, 95% CI)	Totals not selected
6 Epworth Sleepiness Scale	1		mean difference (Fixed, 95% CI)	Totals not selected
7 Symptoms of OSA	1		mean difference (Fixed, 95% CI)	Totals not selected