Hofman 1994.

Study characteristics
Methods	Study objective: to determine the effectiveness in pressure‐sore prevention of the DeCube mattress versus standard mattress in patients with a femoral‐neck fracture and a concomitant high risk for the development of pressure sores. Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 1 and 2 weeks Number of arms: 2 Single centre or multi‐sites: single centre Study start date and end date: not described Setting: hospital
Participants	Baseline characteristics Inclusion criteria: all patients admitted to hospital with a femoral‐neck fracture and with a pressure‐sore risk score of 8 points or more Exclusion criteria: patients with pressure sores of grade 2 or more on admittance Sex (M:F): 5:16 in DeCube mattress; 1:22 in standard mattress Age (years): mean 85.0 (SD 8.1) in DeCube mattress; 83.9 (6.9) in standard mattress Baseline skin status: mean score 10 (SD 1.6) in DeCube mattress; 10.4 (1.4) in standard mattress. All at high risk (according to a scale in the 1985 Dutch consensus meeting, score ≥ 10) Group difference: no difference Total number of participants: 46 individuals randomised (2 incorrectly randomised); 42 analysed at 1 week; 36 analysed at 2 weeks Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Comfortex DeCube mattress Description of interventions: Comfortex DeCube mattress (Comfortex, Winona, USA) but no further description. "an orthopaedic technician developed a mattress with a foam core and multiple small cubes that could be removed beneath bony prominences for pressure relief, similar to the DeCube Comfortex mattress" (Hofman 1994); "Highly resilient layer of cushioning materials spans over surface and conforms to the body" from product description in Direct Supply (https://store.directsupply.com/Product/decube-foam-mattress-2519567). NPIAP S3I classification: non‐powered, reactive foam surface; high‐specification (high resilience) foam Co‐interventions: standard protocol Number of participants randomised: n = 23 (2 incorrectly randomised) Number of participants analysed: n = 20 at 1 week; 17 at 2 weeks Standard hospital mattress Description of interventions: standard Vredestein polypropylene SG 40 hospital mattress (Vredestein, Netherlands) NPIAP S3I classification: standard hospital surface Co‐interventions: standard protocol Number of participants randomised: n = 23 Number of participants analysed: n = 22 at 1 week; 19 at 2 weeks
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: 1 week; 2 weeks Reporting: fully reported Measurement method (e.g. scale, self‐reporting): graded using 0 = normal skin; 1 = persistent erythema of the skin; 2 = blister formation; 3 = superficial (sub)cutaneous necrosis; and 4 = deep subcutaneous necrosis Definition (including ulcer stage): number of patients with maximum pressure‐sore gradings on any location and defined grade 2 or more as clinically relevant pressure sores Dropouts: 3 of 23 in DeCube and 1 of 23 in standard mattress at 1 week; 6 of 23 in DeCube and 4 of 23 in standard at 2 weeks Notes (e.g. other results reported): 1 week data: 5 of 20 in DeCube (3 grade 2, 1 grade 3, and 1 grade 4) and 14 of 22 in standard (4 grade 2 and 10 grade 3); 2‐week data: 4 of 17 in DeCube (1 grade 2 and 3 grade 3) and 13 of 19 in standard (5 grade 2, 5 grade 3 and 3 grade 4) 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: Pressure ulcer incidence by sacrum, trochanters, shoulders, left hip fracture and right hip fracture (reported by authors but not extracted)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Each group of 6 consecutively admitted patients was randomly divided into 3 patients nursed preoperatively and postoperatively on the standard Vredestein polyproleen [polypropylene] SG 40 hospital mattress (Vredestein, Netherlands) and 3 nursed on the Comfortex DeCube" Comment: the method of randomisation was not described.
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Outcome group: primary outcome Quote: "The study was not blinded with respect to observer or nurse" Comment: high risk of bias because clearly blinding was not implemented.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome group: primary outcome Quote: "The study was not blinded with respect to observer or nurse" Comment: high risk of bias because clearly blinding was not implemented.
Incomplete outcome data (attrition bias) All outcomes	High risk	Outcome group: primary outcomes Comment: high risk of bias because 10 of 46 individuals missed at 2 weeks.
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	Unclear risk	Comment: the study appears to have been stopped early. It is not clear whether this interim analysis was pre‐planned in advance of data collection ‐ the sample size calculation doesn't seem to take this into account.