1. All reported adverse events.

Study ID	Alternating pressure (active) air surfaces	Foam surfaces	Comment
Nixon 2019	Related and unexpected serious adverse events: 0 Expected adverse events/ serious adverse events: 163/1017 The proportion of deaths: 82/1017, 8.1% Re‐admission rates: 82/1017, 8.1% Fall rates: 152/1017, 14.9%	Related and unexpected serious adverse events: 0 Expected adverse events/ serious adverse events: 167/1013 The proportion of deaths: 84/1013, 8.3% Re‐admission rates: 62/1013, 6.1% Fall rates: 159/1013, 15.7%	Similar between groups
Rosenthal 2003	See comment	See comment	One death; but the authors did not specify which group the death was in.
Sauvage 2017	Serious adverse events: 2 deaths, a massive septic shock with acute pulmonary oedema and a decompensation of an insulin‐dependent diabetes. 20 adverse events, including 2 discomforts.	No serious adverse events reported 20 adverse events, including 1 hyperalgesia.	Events other than discomfort and hyperalgesia did not involve the mattresses.