Collier 1996.

Study characteristics
Methods	Study objective: to compare 8 new foam mattresses with a new standard 180 mm hospital mattress, and to define their ability to reduce the incidence of pressure sore formation and to provide comfort Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: not described Number of arms: 8 (7 of them were combined into 1 arm) Single centre or multi‐sites: single centre Study start date and end date: not described Setting: a hospital
Participants	Baseline characteristics Inclusion criteria: not described Exclusion criteria: not described Sex (M:F): overall 40:59 Age (years): not described Baseline skin status: all patients were included irrelevant of Waterlow Score Group difference: not described Total number of participants: not described Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Clinifloat Description of interventions: Clinifloat (SSI Medical Services Ltd) NPIAP S3I classification: non‐powered, reactive foam surface; insufficient information for specifying foam quality Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 11 Omnifoam Description of interventions: Omnifoam (HNE Healthcare). Extra information from Santy 1994: "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 Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 11 Softform Description of interventions: Softform (Medical Support System) NPIAP S3I classification: non‐powered, reactive foam surface; high‐specification according to Gray 1994 Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 12 STM5 Description of interventions: STM5 (Servies to Medicine) NPIAP S3I classification: non‐powered, reactive foam surface; insufficient information for specifying foam quality Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 10 Therarest Description of interventions: Therarest (KCI Medical Ltd) NPIAP S3I classification: non‐powered, reactive foam surface; insufficient information for specifying foam quality Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 13 Transfoam Description of interventions: Transfoam (Karomed) NPIAP S3I classification: non‐powered, reactive foam surface; high‐specification according to Gray 2000 Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 10 Vapourlux Description of interventions: Vapourlux (Parkhouse) NPIAP S3I classification: non‐powered, reactive foam surface; insufficient information for specifying foam quality Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 14 NHS standard contract 130 mm foam mattress Description of interventions: NHS standard contract 130 mm foam mattress (Manufacturer: Reylon Ltd) NPIAP S3I classification: non‐powered, reactive foam surface; insufficient information for specifying foam quality Co‐interventions: not described Number of participants randomised: not described Number of participants analysed: n = 9
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 Definition: "Deterioration of skin condition as a result of the effects of pressure" reported is deemed to cover the condition of pressure ulcer Dropouts: not described Notes: no deterioration of skin condition across groups Time to pressure ulcer incidence Reporting: not reported Support‐surface‐associated patient comfort Outcome type: Time points: not described Reporting: partially reported Measurement method (e.g. scale, self‐reporting): assessed using a standardised question and visual rating scale (1 = poor, 10 = excellent) Definition: not described Dropouts: not described Notes: range of patient comfort assessments 5 to 7 in Clinifloat (n = 11); 0 to 0 in NHS Standard (n = 9); 3 to 8 in Omnifoam (n = 11); 8 to 11 in Softform (n = 12); 9 to 9 in STM5 (n = 10); 8 to 8 in Therarest (n = 13); 2 to 8 in Transfoam (n = 10); 10 to 10 in Vapourlux (n = 14) 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: No
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Mattresses were randomly allocated to patients on admission as available" Comment: unclear if 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: all outcomes Quote: "The mattresses were coded numerically ... with their identification number clearly displayed above the bed ... To reduce bias, ... only the principal investigator and the ward link nurse knew the identification of each mattress" Comment: unclear risk of bias for both pressure ulcer and comfort outcomes because it is unclear if these foam mattresses are similar to each other and if investigator and the link nurse are involved in patient care.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome group: all outcomes Quote: "Patients were periodically reassessed ... and any evidence of skin deterioration was documented ... conducted at least weekly throughout their period in hospital" Comment: high risk of bias for both pressure ulcer and comfort outcomes because it is unlikely that blinding was implemented for participants and personnel given the information provided. Self‐reported comfort outcome cannot be measured in a blinded way.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: all outcomes Comment: no attrition identified.
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.