Vyhlidal 1997.

Study characteristics
Methods	Study objective: this study compares these 2 foam products [MAXIFLOAT foam mattresses and the Iris 3000 foam overlay] based on pressure ulcer incidence in an at‐risk population Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 21 days Number of arms: 2 Single centre or multi‐sites: single centre Study start date and end date: not described Setting: a 250‐bed, teaching, skilled nursing facility (hospital‐based facility)
Participants	Baseline characteristics Inclusion criteria: (a) newly admitted to the skilled nursing facility with an estimated stay of at least 10 days; (b) free of existing pressure ulcers; and (c) at‐risk for pressure ulcer development (Braden Scale score < 18 with a subscale score of < 3 in sensory perception, mobility, or activity levels) Exclusion criteria: not described Sex (M:F): 9:11 in each group Age (years): mean 80.16 (SD 8.96) in Iris 3000; 74.25 (17.49) in MAXIFLOAT Baseline skin status: mean Braden scores 14.5 (SD 1.61) in the Iris 3000; 14.7 (2.28) in the MAXIFLOAT Group difference: people in the MAXIFLOAT group were significantly heavier (in terms of the body mass index) than those in the Iris 3000 group (t = 2.6, P = 0.013); the MAXIFLOAT group also stayed on the mattress longer (t,= 2.24, P = 0.03) Total number of participants: n = 40 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Iris 3000 Description of interventions: the Iris 3000 is a 4‐inch, 1.8‐lb density foam overlay with a flat, dimpled surface NPIAP S3I classification: non‐powered, reactive foam surface; density of 28.8 kg/m3 foam Co‐interventions: received standards of care Number of participants randomised: n = 20 Number of participants analysed: n = 20 MAXIFLOAT Description of interventions: the MAXIFLOAT foam mattress is a replaceable‐parts mattress ... (b) a 1½‐inch thick, 2.4‐lb dual IFD (indentation force load deflection), luxury‐grade, high‐resiliency, antimicrobial foam; (c) a centre core 29‐lb IFD flame‐retardant, polyurethane foam with exclusive precision die cuts and a 16‐inch long by 26‐inch wide non‐removable polyester fibber heel pillow ... NPIAP S3I classification: non‐powered, reactive foam surface; high specification (high‐resiliency, 29 lb IFD, polyurethane) foam. Co‐interventions: received standards of care Number of participants randomised: n = 20 Number of participants analysed: n = 20
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): classification system used in the Bergstrom Skin Assessment Tool that is equivalent to NPIAP/EPUAP system Definition (including ulcer stage): number of subjects with new pressure ulcers of stage 1 (least severe) to stage 4 (most severe) used in the Bergstrom Skin Assessment Tool Dropouts: no missing Notes (e.g. other results reported): 12 of 20 (60%) in the Iris 3000 (4 Stage I and 8 Stage II) and 5 of 20 (25%) in MAXIFLOAT (2 Stage I and 3 Stage II) Time to pressure ulcer incidence Outcome type: time‐to‐event Reporting: partially reported Notes: average number of days to pressure ulcer development 6.5 days on Iris 3000 and 9.2 days on MAXIFLOAT (not significantly different between groups, t[15] = 1.0095, P = 0.3288) 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: Cost analysis
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Subjects meeting the admission criteria were randomly assigned by lot by the investigator who obtained the consent to use either the Iris 3000 or the MAXIFLOAT ... subjects were randomly assigned by research interviewer by drawing assignment out of a hat" 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	Outcome group: all outcomes Comment: no information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome group: all outcomes Comment: no information provided.
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.