Comparison 2. Alternating pressure (active) air surfaces compared with reactive air surfaces.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 Proportion of participants developing a new pressure ulcer	6	1648	Risk Ratio (M‐H, Random, 95% CI)	1.61 [0.90, 2.88]
2.2 Time to pressure ulcer development	1		Hazard Ratio (IV, Random, 95% CI)	2.25 [1.05, 4.83]