Van Leen 2018.

Study characteristics
Methods	Study objective: to test the pressure ulcer (PrU) preventive effect of this system [a pressure‐relieving, shear stress‐diminishing, and microclimate‐controlling skin interface multilayer support system (Bedcare; Sense Textile, ‘s‐Hertogenbosch, the Netherlands)] compared with a viscoelastic foam mattress alone Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 12 weeks of study period Number of arms: 2 Single centre or multi‐sites: multi‐sites Study start date and end date: not described Setting: nursing homes
Participants	Baseline characteristics Inclusion criteria: all residents at medium/high risk (Braden score < 16) of PrUs ... age older than 60 years, life expectancy greater than 3 months, and informed consent Exclusion criteria: a PrU in the last 3 months, participation in a comparable trial, or a physical and/or mental condition that could interfere with participation (such as sepsis, immune disease, palliative status) Sex (M:F): 71.8% of 103 females in multilayer mattress; 69.9% of 103 females in viscoelastic foam Age (years): 83.1 in multilayer mattress; 81.7 in viscoelastic foam Baseline skin status: Braden score 13.1 in multilayer mattress; 13.3 in viscoelastic foam; at risk but no existing ulcers Group difference: no difference Total number of participants: n = 206 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Multilayer mattress system Description of interventions: received the same new high‐quality viscoelastic foam mattress together with the new multilayer system (total thickness, 13 mm) (Bedcare; Sense Textile, ‘s‐Hertogenbosch, the Netherlands), consisting of 3 separate layers, each with an independent function: 1. The Mini Overlay System (MOS; thickness, 9.5 mm), a 3‐dimensional pressure‐relieving spacer fabric ... 2. A textile mattress cover (made of polyester and elastan, covered with polyurethane; 0.5 mm) ... 3. Stay and Transfer Sheet (STS; thickness, 3 mm), a 3‐dimensional knitted spacer fabric NPIAP S3I classification: non‐powered, reactive surface; undefined in NPIAP S3I Co‐interventions: when out of bed, all residents sat on a PrU‐preventive air pillow Number of participants randomised: n = 103 Number of participants analysed: n = 103 Viscoelastic foam mattress Description of interventions: high‐quality viscoelastic foam mattress (Formafoam, Kabelfabriek Eupen, Belgium) NPIAP S3I classification: non‐powered, reactive foam surface; viscoelastic foam Co‐interventions: when out of bed, all residents sat on a PrU‐preventive air pillow Number of participants randomised: n = 103 Number of participants analysed: n = 103
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: not described Reporting: partially reported Measurement method (e.g. scale, self‐reporting): not described in the paper but mentioned in trial register as "definitions Richtlijn preventie van decubitus V&VN 2009" Definition (including ulcer stage): the development of a category 2, 3, or 4 PrU according to definitions Richtlijn preventie van decubitus V&VN 2009 Dropouts: none Notes (e.g. other results reported): 9 of 103 in multilayer mattress (3 category 2 on sacral, 3 category 2 on heel, 2 category 2 on others; 1 category 3 on heel and 1 category 3 on other); 5 patients of 103 in viscoelastic foam (2 category 2 on sacral, 3 category 2 on others; 3 category 3 on heel); P = 0.180 Time to pressure ulcer incidence Reporting: not reported Support‐surface‐associated patient comfort Reporting: not reported All reported adverse events using allocated support surfaces Notes: no adverse events were reported during the study period Health‐related quality of life (HRQOL) Reporting: not reported Cost‐effectiveness Reporting: not reported
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomization into 2 groups was performed by using the Castor randomization software (version 1.44; Mionix, Malmo¨, Sweden)." Comment: low risk of bias because of the use of a proper randomisation method.
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: no information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "Data were collected weekly, controlled by an independent research nurse." Comment: unclear risk of bias because of insufficient information.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: low risk of bias because it appears to include all 206 patients in analysis.
Selective reporting (reporting bias)	High risk	Comment: high risk of bias because the study protocol is available from https://www.trialregister.nl/trial/4435 and it is clear that the pre‐specified costs outcome is not presented.
Other bias	Low risk	Comment: the study appears to be free of other sources of bias.