Gunningberg 2000.

Study characteristics
Methods	Study objective: to investigate if viscoelastic foam mattresses are more effective than standard hospital mattresses in reducing the incidence of pressure ulcers in patients with hip fractures. Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: post‐operative 14 days Number of arms: 2 Single centre or multi‐sites: single centre Study start date and end date: March and December 1999 Setting: accidents and emergency (A&E) department and the orthopaedic wards of a university hospital
Participants	Baseline characteristics Inclusion criteria: patients aged over 65 years with a suspected hip fracture Exclusion criteria: died, did not have a skin assessment documented on arrival, admitted with pressure ulcers Sex (M:F): 10:38 in viscoelastic foam mattress; 10:43 in standard hospital mattress Age (years): mean 84 (range 66 to 102) in viscoelastic foam mattress; 85 (67 to 96) in standard hospital mattress Baseline skin status: mean Modified Norton score (at risk = a total score of ≤ 21): 18.6 (range 10 to 25) in viscoelastic foam mattress; 18.8 (11 to 24) in standard hospital mattress; excluding those with pressure ulcers Group difference: no difference Total number of participants: 101 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Viscoelastic foam mattress Description of interventions: placed on a 10‐centimetre thick viscoelastic foam mattress (7 cm viscoelastic foam plus 3 cm 35 kg/m3 foam: Tempur‐Pedic, Fagerdala, Sweden) immediately on arrival in A&E. A 7 cm viscoelastic foam overlay was placed on the standard mattresses used in the wards. NPIAP S3I classification: non‐powered, reactive foam surface; high‐specification foam (viscoelastic foam plus density of 35 kg/m3) Co‐interventions: not described Number of participants randomised: n = 48 Number of participants analysed: n = 48 Standard hospital mattress Description of interventions: placed on the routine standard trolley (5 cm mattress) and then on the standard hospital mattress (10 cm foam 50 kg/m3: Prodenso, Ranson AB, Sweden) when transferred to the ward NPIAP S3I classification: standard hospital surface Co‐interventions: not described Number of participants randomised: n = 53 Number of participants analysed: n = 53
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: 2 weeks Reporting: fully reported Measurement method (e.g. scale, self‐reporting): ward nurses rated and expert nurses confirmed Definition (including ulcer stage): presence or absence of a pressure ulcer (including grade I ulcers) graded by NPUAP system Dropouts: no dropouts Notes (e.g. other results reported): 12 of 48 in viscoelastic foam mattress (8 Grade I; 4 Grade II; 0 Grade III, 0 Grade IV); 17 of 53 in standard hospital mattress (9 Grade I; 7 Grade II; 0 Grade III; 1 Grade IV) Time to pressure ulcer incidence Reporting: not reported Support‐surface‐associated patient comfort Outcome type: continuous Time points: 2 weeks Reporting: partially reported Measurement method (e.g. scale, self‐reporting): self‐rated using a standardised question: ‘How did you experience the comfort of the hospital mattress?’ and ‘very good’ = 5, ‘good’ = 4, ‘adequate’ = 3, ‘bad’ = 2 and ‘very bad’ = 1 Definition: patients’ perceptions of mattress comfort Dropouts: 27 dropouts in viscoelastic foam mattress; 33 in standard hospital mattress Notes: mean rating of comfort: 4.2 in viscoelastic foam mattress; 4.0 in standard hospital mattress; 38 of 41 reported good or very good comfort in both groups 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
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "On arrival in A&E patients with a suspected hip fracture were randomised to an experimental or a control group with concealed allocation" Comment: the method of randomisation was not reported.
Allocation concealment (selection bias)	Unclear risk	Quote: "On arrival in A&E patients with a suspected hip fracture were randomised to an experimental or a control group with concealed allocation" Comment: the method of concealing allocation was not reported.
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	Low risk	Outcome group: primary outcome Quote: "The pressure ulcer nurse on the ward usually performed the assessments on the fourth postoperative day and at discharge. The pressure ulcers were photographed ... The ulcers in these photos were graded by an expert nurse ... who was blinded to treatment, and compared with the classifications performed by the nurses in A&E and on the wards ... an excellent agreement" Comment: low risk of bias because the expert nurse who was blinded to treatment had assessments consistent with the ward nurses, meaning ward nurses' outcome assessment was unlikely to be influenced by treatment. Outcome group: comfort outcome Comment: high risk of bias because it is impossible to blind patients to self‐reported outcome measure.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: primary outcome Comment: no missing data. Outcome group: comfort outcome Quote: "Forty‐one patients (21 in the experimental and 20 in the control group) with a mean age of 84 years (SD: 7.6, 67–102) answered this question" Comment: high risk of bias because 27 of 48 in viscoelastic foam group and 33 of 53 in standard hospital mattress group missed.
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.