Table 1.

Rating scales, summary results and comparisons across the primary outcome questionnaire domains

	PPE	Q8 speak to staff	Q9 be heard by staff	Q10 speak to patient	Q11 be heard by patient	Q14 how safe does it feel	Q17 comfortable
Rating scale	From:	0—no confidence	0—no confidence	0—no confidence	0—no confidence	1—very unsafe	1—very uncomfortable
	To:	10—fully confident	10—fully confident	10—fully confident	10—fully confident	7—very safe	7—very comfortable
RPE type	FFP3	5.1 (2.4) (1–10)	4.9 (2.3) (1–10)	4.8 (2.4) (1–10)	4.7 (2.5) (1–10)	5.4 (1.0) (3–7)	3 (1.4) (1–6)
	Bubble	7.5 (2.4) (1–10)	7.1 (2.3) (1–10)	7.8 (2.1) (2–10)	7.4 (2.4) (1–10)	6.2 (0.9) (3–7)	5.6 (1.6) (1–7)
Comparison	Mean difference	2.38	2.16	2.99	2.7	0.73	2.68
	95% CI	1.66 to 3.11	1.45 to 2.88	2.36 to 3.62	1.97 to 3.43	0.45 to 0.99	2.23 to 3.14
		Favours Bubble	Favours Bubble	Favours Bubble	Favours Bubble	Favours Bubble	Favours Bubble
	Adjusted p value	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001

FFP, filtering face piece; RPE, respiratory protective equipment.