Cavicchioli 2007.

Methods	RCT with follow‐up of 2 weeks.
Participants	Acute and long‐term care participants deemed at risk of pressure ulceration (Braden score < 17 activity or mobility sub‐scales < 3 respectively). Patients had an expected admission of at least 2 weeks. Patients could have 1 grade 1 pressure ulcer at baseline, but were excluded if they had more; or the ulcer was grade 2 or above. Baseline balance for age, sex and Braden score in the randomised groups.
Interventions	1. High‐tech (Duo 2, Hill Rom) mattress on alternating low‐pressure setting (n = 86). 2. High‐tech (Duo 2, Hill Rom) mattress on continuous low‐pressure setting (n = 84).
Outcomes	Number of participants with Incidence pressure ulcer (blinded outcome assessment at study end): Grade 1: 1. Alternating low‐pressure 1% (1/69); 2. Continuous low‐pressure 0/71. Grade 2: 1. Alternating low‐pressure 1% (1/69); 2. Continuous low‐pressure 1% (1/71).
Notes	This was a 3‐armed study. There was a 2‐armed RCT, as described, and a control group (standard mattress), which was not formed by randomisation and not included here. Blinded outcome assessment was conducted for the randomised groups. Follow up figures were: 1. 69 (4 deaths, 8 participants discharged before final assessment, and 5 classed as not having completed the study due to non‐concordance); 2. 71 (5 deaths, 4 discharged and 4 classed as non‐concordant). Not ITT.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants not randomly allocated to the 3 groups from same pool of patients. Controls from another hospital. Only patients in high tech groups appeared to be randomised "by means of a sealed envelope".
Allocation concealment (selection bias)	Unclear risk	Unclear.
Blinding (performance bias and detection bias) Pressure ulcer incidence	Low risk	External observer was blinded to which treatment mattress was in use.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reasons for attrition and exclusion reported.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes reported.
Free of other bias ‐ were groups similar at baseline regarding the most important prognostic indicators?	High risk	"The two treatments groups were assessed as at greater risk of pressure ulceration than the control group both at baseline (p <0.001) and the study end (p <0.005)."
Free of other bias ‐ was the timing of the outcome assessment similar in all groups?	Low risk	2‐week study period with assessments taking place at the beginning and end of the study.