Direct comparisons	Number of studies	Study design, no. of multi‐arm studies (% of total participants)	Median of follow‐up	Care settings (% of total participants)	Number of events/ number of total participants (%)	Male (%)	Female (%)	Median of average age reported (years)	Baseline skin status (% of total participants)	Overall risk of bias level (% of total participants)
Alternating pressure (active) air surfaces vs foam surfaces	2	Two‐arm RCTs	60 days	Acute care setting (96%), Long‐term care setting (4%)	175/2105 (8%)	929 (44%)	1173 (56%)	82	At risk, free of ulcers (100%)	Low (96%); High (4%)
Alternating pressure (active) air surfaces vs foam surfaces plus 4‐hourly turning	1	Two‐arm RCT	20 weeks	Acute care setting (100%)	69/447 (15%)	163 (37%)	283 (63%)	82	At risk, free of ulcers (100%)	Low (100%)
Alternating pressure (active) air surfaces vs reactive air surfaces	1	Two‐arm RCT	14 days	Long‐term care setting (100%)	26/308 (8%)	71 (23%)	237 (77%)	87	At risk, free of ulcers (100%)	High (100%)
Foam surfaces vs 'standard hospital surfaces'	3	Two‐arm RCTs	11.5 days	Acute care setting (94%); Operating room (6%)	181/3072 (6%)	516 (38%)	827 (62%)	75	At risk, free of ulcers (100%)	Unclear (62%); High (38%)
Reactive sheepskin surfaces vs 'standard hospital surfaces'	3	Two‐arm RCTs	30 days	Acute care setting (58%); Long‐term care setting (42%)	248/1281 (19%)	533 (40%)	793 (60%)	73	At risk, free of ulcers (100%)	High (100%)