Russell 2003a.

Study characteristics
Methods	Study objective: to determine whether a viscoelastic polymer (energy absorbing) foam mattress was superior to a standard hospital mattress for pressure ulcer prevention and to analyse the cost‐effectiveness in comparison with standard hospital mattresses. Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: median days 11 (25th to 75th percentile 6 to 20) in CONFORM‐Med; 12 (7 to 22) in standard mattress Number of arms: 2 Single centre or multi‐sites: multi‐sites Study start date and end date: May 1999 to June 2000 Setting: elderly acute care, rehabilitation, and orthopedic wards of hospitals.
Participants	Baseline characteristics Inclusion criteria: all patients admitted to acute elderly care and orthopedic wards at hospital 1; elderly rehabilitation wards at hospital 2; and acute elderly care wards at hospital 3 within the preceding 72 hours, who are aged 65 years and older; a pressure ulcer (PrU) risk of 15 to 20 on the Waterlow score, which is based on physiologic, demographic, and disease‐specific features; consent to regular examination of pressure areas Exclusion criteria: obesity ( > 341 lb [ > 155 kg]); previous trial participation; refusal of consent Sex (M:F): 391:777 across groups Age (years): median 83 (25th to 75th percentile: 79 to 87) Baseline skin status: mean Waterlow 17.07 (SD 1.76) in CONFOR‐Med; 16.98 (1.75) in standard mattress Group difference: no difference Total number of participants: 1168 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics CONFOR‐Med mattress/cushion combination Description of interventions: CONFOR‐Med mattress/cushion combination (Aearo Company, Indianapolis, IN) constructed from a 3‐inch layer of viscoelastic foam and a 3‐inch layer of standard polyurethane foam. Viscoelastic (energy absorbing) polymer foam mattresses ... constructed of a single foam density or several foams of different densities in layers of progressively less deformable foam, down to a standard, resilience cushioning polyurethane foam base. The foam surface molds to the patient’s body shape and, by reducing high‐pressure zones ... NPIAP S3I classification: non‐powered, reactive foam surface; multi‐layered, viscoelastic and polyurethane foam mattress Co‐interventions: not described Number of participants randomised: n = 564 Number of participants analysed: n = 562 Standard mattress/cushion combination Description of interventions: King’s Fund, Linknurse, Softfoam, or Transfoam, or a King’s Fund mattress with a Spenco or Propad mattress overlay NPIAP S3I classification: standard hospital surfaces Co‐interventions: not described Number of participants randomised: n = 604 Number of participants analysed: n = 604
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: not specified Reporting: partially reported Measurement method (e.g. scale, self‐reporting): Definition (including ulcer stage): development of non‐blanching erythema or worse, graded using the Torrance scale (blanching erythema = a Torrance grade I ulcer, and non‐blanching erythema = a Torrance grade II ulcer) Dropouts: 2 excluded from CONFOR‐Med Notes (e.g. other results reported): 48 of 562 in CONFOR‐Med; 66 of 604 in standard mattress. The authors also reported subgroup analysis by whether patients had blanching erythema on admission. These data not extracted. Time to pressure ulcer incidence Outcome type: time‐to‐event Time points: not specified Reporting: partially reported Measurement method (e.g. scale, self‐reporting): see above Definition (including ulcer stage): the number of participants who had not developed an ulcer divided by the total number of participants for each trial day Dropouts: see above Notes: figure 2a, 2b reported; HR 0.85 (95% CI 0.55 to 1.31) estimated by the review authors by using methods described in Tierney 2007 Support‐surface‐associated patient comfort Outcome type: continuous Time points: not specified Reporting: partially reported Measurement method (e.g. scale, self‐reporting): self‐reported, using a 10‐point comfort questionnaire (1 = completely relaxed, 10 = unbearable pain) Definition: the comfort of the mattresses Dropouts: "Of 1168 participants, 706 expressed opinions regarding comfort" Notes: no significant differences in comfort assessment were found. The average assessment of comfort for both mattress types ... with levels of 2.33 ± 0.98 and 2.46 ± 1.0 (P = NS) on a 1 to 10 scale. All reported adverse events using allocated support surfaces Reporting: not reported Health‐related quality of life (HRQOL) Reporting: not reported Cost‐effectiveness Outcome type: continuous Reporting: partially reported Measurement method (e.g. scale, self‐reporting): 2 cost‐effectiveness ratios were calculated: (1) a cost per any PrU avoided; and (2) a cost per non‐blanching erythema (or worse) avoided. A cost‐effectiveness acceptability curve was also generated. Definition: cost‐effectiveness acceptability curve plots the probability of the cost‐effectiveness of the new mattress against a range of cost‐effectiveness ratios. Notes: an approximately 88% chance that the experimental equipment is the dominant option (i.e. more effective and less costly) ... a 95% chance that the experimental equipment produces a cost per averted non‐blanching erythema area of GBP 100 (i.e. USD 140) or less (see Figure 3). Outcomes that are not considered in this review but reported in trials: Development of blanching erythema Length of time spent on secondary equipment Nursing intervention
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "On admission, participants were randomised to the standard equipment group or the experimental equipment group" Quote: "Equipment allocation at 2 sites was made by converting random numbers (Excel; Microsoft Corp, Redmond, WA) on a 50:50 basis ..." Comment: low risk of bias because study used a proper randomisation method.
Allocation concealment (selection bias)	Low risk	Quote: "At site 3, trial numbers were allocated sequentially and the patient chose from 1 of 2 opaque envelopes" Quote: "At sites 1 and 2, each trial ward kept sealed, opaque envelopes containing a trial number and equipment allocation" Quote: "All patients were enrolled into the trial by a research nurse, who carried out the randomization by taking an envelope" Comment: low risk of bias because a proper concealment was likely used.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Outcome group: primary outcome Quote: "Because ... the experimental mattress surface is distinctive, data collection could not be blinded" Quote:"Although ... it as impossible to blind the research nurses to mattress assignment" Comment: high risk of bias because it is unlikely participants and personnel were blinded.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome group: primary outcome Quote: "The participants’ pressure areas were assessed daily by ward nurses ... A research nurse was immediately notified of any significant deterioration ... completed data collection proformas weekly" Quote: "Because the data collection team examined participants at bedside and the experimental mattress surface is distinctive, data collection could not be blinded" Comment: high risk of bias because outcome assessment was not blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: primary outcome Quote: "The primary analysis was intention‐to‐treat and involved all randomised participants other than the 2 excluded participants" Comment: low risk of bias because ITT analysis is done.
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.