Daechsel 1985.

Study characteristics
Methods	Study objective: to assess 2 commonly used special mattresses in a randomised trial involving adult non‐geriatric chronic neurologic patients Study design: randomised controlled trial Study grouping: parallel group Duration of follow‐up: 3 months Number of arms: 2 Single centre or multi‐sites: single centre Study start date and end date: not described Setting: long‐term care hospital for chronic neurologic conditions
Participants	Baseline characteristics Inclusion criteria: consenting patients in a long‐term care hospital for chronic neurologic conditions ... a) between 19 and 60 years of age, b) free of any evidence of skin breakdown two weeks prior to the study, and c) considered to be at high risk of developing pressure ulcers based on assessments conducted by the ward team [Norton scale score of 14 or less; and clinical judgement] Exclusion criteria: none Sex (M:F): 10:6 in alternating air mattress; 6:10 in Silicore mattress Age (years): mean 42.6 (SD 13.7) in alternating air mattress; 38.5 (13.82) in Silicore mattress Baseline skin status: mean Norton score 13.35 (SD 1.86) in alternating air mattress; 12.97 (2.28) in Silicore mattress. Group difference: no difference Total number of participants: 32 Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Alternating air mattress Description of interventions: "... consisted of an electrically driven pump connected to a heavy‐duty plastic mattress ... composed of honey combed 4‐inch air cells, which alternately inflate and deflate when in operation ... placed over a standard hospital spring mattress or 4‐inch foam mattress and supported by a standard hospital bedframe" NPIAP S3I classification: powered, alternating pressure (active) air surface Co‐interventions: usual care including repositioning and additional preventive aids (including heel and ankle protectors, sheepskins and bed cradles) Number of participants randomised: n = 16 Number of participants analysed: n = 16 Silicore mattress Description of interventions: "a reversible mattress composed of siliconized hollow fibers in an interwoven mesh that accommodates the body surface and decreases pressure ... placed over a standard hospital spring mattress or 4‐inch foam mattress and supported by a standard hospital bedframe" NPIAP S3I classification: non‐powered, reactive fibre‐filled surface Co‐interventions: usual care including repositioning and additional preventive aids (including heel and ankle protectors, sheepskins and bed cradles) Number of participants randomised: n = 16 Number of participants analysed: n = 16
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: 3 months Reporting: fully reported Measurement method (e.g. scale, self‐reporting): measured by 1 investigator using the Exton‐Smith scale Definition (including ulcer stage): skin condition of degrees of ulcers graded on the Exton‐Smith scale (0 = none, 1 = persistent erythema, 2 = localised blister, 3 = superficial sore, 4 = deep sore, 5 = extensive gangrenous sore) Dropouts: no dropouts Notes (e.g. other results reported): 4 of 16 individuals in alternating air mattress; 4 of 16 in Silicore mattress. Severity of ulcers graded and numbers by grade not reported and not extracted. Time to pressure ulcer incidence Reporting: not reported Support‐surface‐associated patient comfort Time points: 3 months Reporting: partially reported Measurement method (e.g. scale, self‐reporting): not reported Notes: "the patients did not indicate a particular like or dislike of the type of mattress to which they were assigned" 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: Equipment condition
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "All were randomly assigned to one of the two types of mattresses" Comment: the method of randomisation was not described.
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Outcome group: primary outcome Comment: no information provided.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome group: primary outcome Quote: "one of the investigators (DD) conducted weekly skin checks of the subjects" Comment: high risk of bias for pressure ulcer incidence outcome because it is unlikely that the investigator who assessed skin conditions was blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: primary outcome Quote: "Thirty‐two patients met the criteria for this study ... all admitted to the trial and completed it" Comment: no missing data.
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.