Takala 1996.

Study characteristics
Methods	Study objective: to test the hypothesis that this device [a new, easily adjustable anti‐decubitus mattress] would be clinically effective in the prevention of pressure sores in patients requiring prolonged intensive care Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 14 days Number of arms: 2 Single centre or multi‐sites: single centre Study start date and end date: not described Setting: intensive care unit (hospital)
Participants	Baseline characteristics Inclusion criteria: non‐trauma patients admitted to intensive care unit (ICU) expected to stay > 5 days Exclusion criteria: patients with accidental injuries Sex (M:F): 12:9 in Carital Optima; 13:6 in standard hospital foam mattress Age (years): mean 60 (SD 16) in Carital Optima; 63 (12) in standard hospital foam mattress Baseline skin status: Norton below 8 across groups (high risk) Group difference: no difference Total number of participants: n = 40 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Pressure‐relieving mattress Description of interventions: pressure‐relieving mattress (Carital Optima, Carital Ltd, Tuusula, Finland). Carital Optima, constant low pressure mattress comprising 21 double air bags on a base, reduce the pressure on the skin by distributing the patient's weight over a maximum contact area. Formed of the separate upper layer of the cells ... pressure within the upper layer of cells and in the three compartments of the lower layer of cells can be adjusted separately (Takala 1996). Additional source of information from Carital-Optima-Brochure-1.pdf (directhealthcaregroup.com) indicates that Carital Optima needs electricity to be functional NPIAP S3I classification: powered, reactive air surface Co‐interventions: not described Number of participants randomised: n = 21 Number of participants analysed: n = 21 Standard hospital mattress Description of interventions: standard hospital mattress (10‐centimetre thick foam mattress, density 35 kg/m3, Espe Inc, Kouvola, Finland). NPIAP S3I classification: non‐powered, reactive foam surface; high specification (density 35 kg/m3) foam Co‐interventions: not described Number of participants randomised: n = 19 Number of participants analysed: n = 19
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: 14 days Reporting: partially reported Measurement method (e.g. scale, self‐reporting): graded by Shea criteria Definition (including ulcer stage): the development of pressure ulcers graded by Shea criteria Dropouts: intention‐to‐treat (ITT) analysis Notes (e.g. other results reported): 0 of 21 in pressure‐relieving mattress; 7 of 19 in standard hospital mattress (with a totality of 13 ulcers: 9 Shea grade 1A; 4 grade 1B) Time to pressure ulcer incidence Reporting: not reported Support‐surface‐associated patient comfort Reporting: not reported All reported adverse events using allocated support surfaces Reporting: not reported Health‐related quality of life (HRQOL) Reporting: not reported Cost‐effectiveness Reporting: not reported Outcomes that are not considered in this review but reported in trials: Interface pressure
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Those with an expected ICU stay exceeding five days were randomly assigned to be treated on either ..." Comment: unclear risk of bias because a proper randomisation criteria is unspecified.
Allocation concealment (selection bias)	High risk	Comment: randomisation influenced by mattress availability; therefore, allocation not concealed.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Outcome group: pressure ulcer outcome Quote: “The study was not blinded, since the severity of illness of the patients precluded their transfer for evaluation of the skin condition by a blinded reviewer, and the type of mattress in the bed could not be blinded” Comment: high risk of bias because this statement implies blinding of participants and personnel was likely impossible.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome group: pressure ulcer outcome Quote: “The study was not blinded, since the severity of illness of the patients precluded their transfer for evaluation of the skin condition by a blinded reviewer, and the type of mattress in the bed could not be blinded” Comment: high risk of bias as it is clearly stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: pressure ulcer outcome Quote: "Sequential analysis of the primary outcome variable (pressure sore formation) on an intention‐to‐treat basis was done after each block of four patients had completed the treatment" Comment: low risk of bias because ITT analysis was conducted.
Selective reporting (reporting bias)	Low risk	Comment: the study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre‐specified.
Other bias	Low risk	Comment: the study appears to be free of other sources of bias.