Santy 1994.

Study characteristics
Methods	Study objective: to evaluate the effect of 6 types of hospital mattress on the development of pressure damage Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 12 days Number of arms: 6 (of which 1 arm ‐ Omnifoam ‐ has no data available for analysis) Single centre or multi‐sites: single centre Study start date and end date: started April 1993 Setting: orthopaedic trauma wards at Hull Royal Infirmary
Participants	Baseline characteristics Inclusion criteria: elderly patients (aged > 55 y) with hip fracture, with or without pressure ulcers Exclusion criteria: those with a pressure ulcer of grade 3 or 4 at entry Sex (M:F): not reported Age (years): estimated overall 80.24; mean 80.37 in Clinifloat; 79.09 in NHS contract; 81.57 in Transfoam; 78.86 in Therarest; 80.41 in Vaperm Baseline skin status: estimated overall 25.16; mean Waterlow 25.07 in Clinifloat; 24.27 in NHS contract; 25.80 in Transfoam; 24.76 in Therarest; 25.32 in Vaperm; some having Stage 1 and 2 pressure damage Group difference: no difference Total number of participants: n = 552 available Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Clinifloat Description of interventions: Clinifloat (SSI Medical Sevices Ltd) consisting of deep cut foam cubes and evenly distributing patient's weight. NPIAP S3I classification: non‐powered, reactive foam surface Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 87 Omnifoam Description of interventions: Omnifoam (Huntleigh Nesbit Evans Healthcare) made of a high quality multilayer foam construction, ventilated high density foam NPIAP S3I classification: non‐powered, reactive foam surface; high specification (high density) foam Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: no data for analysis; this arm was removed for this review Transfoam Description of interventions: Transfoam (Karomed Ltd) constructed of layered polyurethane foam (150 mm thick), made from a foam density of 30‐33 kg/m3 and hardness 145‐170 N NPIAP S3I classification: non‐powered, reactive foam surface; high specification (density of 30 to 33 kg/m3 and hardness 145 to 170 N) foam Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 136 Therarest Description of interventions: Therarest (KCI Therapeutic Services) with 3 layer therapeutic fire retardant foam core, absorbing and dispersing pressure from high pressure points NPIAP S3I classification: non‐powered, reactive foam surface Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 102 Vaperm Description of interventions: Vaperm (Huntleigh Nesbit Evans Healthcare) constructed from 4 layers of foam increasing in density from 35 kg/m3 at the top to 60 kg/m3 at the bottom with the inner core of high density ventilated foam NPIAP S3I classification: non‐powered, reactive foam surface; high specification (density of 35 kg/m3 to 60 kg/m3) foam Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 116 NHS Contract (150 mm) (Reylon Ltd) Description of interventions: NHS Contract (150 mm) (Reylon Ltd) made of a single block of combustion modified, high resilience polyether foam with a density of 39 to 42 kg/m3 and hardness index of 170 N (130 mm thickness) NPIAP S3I classification: non‐powered, reactive foam surface; high specification (density of 39 to 42 kg/m3 and hardness index of 170 N) foam Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 64
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Reporting: partially reported Measurement method (e.g. scale, self‐reporting): defined by Torrance criteria Definition (including ulcer stage): the need for the patient to be removed from the mattress due to skin deterioration or developing a Stage 3 ulcer. This is not a directly relevant outcome. Dropouts: not described Notes (e.g. other results reported): 8 of 87 cases removed (9.19%) in Clinifloat; 17 of 64 (26.56%) in NHS Contract; 14 of 136 (10.29%) in Transfoam; 11 of 102 (10.78%) in Therarest; 9 of 116 (7.75%) in Vaperm Time to pressure ulcer incidence Not reported Support‐surface‐associated patient comfort Not reported All reported adverse events using allocated support surfaces Not reported Health‐related quality of life (HRQOL) Not reported Cost‐effectiveness Not reported Outcomes that are not considered in this review but reported in trials: Price of mattresses
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Mattresses were randomly allocated to patients using random number tables" Comment: low risk of bias because a proper randomisation method was applied.
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Outcome group: ulcer incidence Comment: no information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome group: ulcer incidence Comment: skin assessment by a research nurse but no information as to whether they were blinded.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Outcome group: ulcer incidence Comment: no information provided.
Selective reporting (reporting bias)	High risk	Comment: 6 types of mattresses were evaluated initially; however, the data collected on the Omnifoam mattress were not analysed because there were insufficient numbers for the results to be significant and they could possibly adversely affect the analysis.
Other bias	Low risk	Comment: the study appears to be free of other sources of bias.