Nakagami 2007.

Methods	Trial design: RCT Trial grouping: within‐participant (participant acting as their own control) Ethics and informed consent: yes Follow‐up period: 3 weeks Sample size estimate: yes, the estimated sample size was 33, and therefore 37 participants were enrolled, assuming a loss to follow‐up of 10% ITT analysis: yes; number randomised: 37; number analysed: 37 Funding: this study was supported by a Grant‐in‐Aid for scientific research from the Ministry of Education, Culture, Sports, Science and Technology, Japan [(B) (2) 16390637]
Participants	Inclusion criteria: aged ≥ 65 Braden score of < 15 Exclusion criteria: impaired judgement lack of consciousness presence of a PU or skin disorder in the study area poor general medical condition inability to position the body in either a right or left lateral position Pretreatment age, years, mean (SD): 86.4 ± 8.2 women: 28 (75.7%) Braden score, mean (SD): 10.4 ± 1.2 bedridden: 37 (100%) body weight: 11 kg, mean (SD): 36.6 ± 2.8 no support surfaces: 11 (29.7%) diagnosis: cerebrovascular disease: 30 (81.1%); heart disease: 10 (27.0%); diabetes mellitus: 4 (10.8%)
Interventions	Intervention group: PPD (dressing with skin adhesive layer (hydrocolloid), a support layer (urethane film) and an outer layer of multi filament nylon fibres applied to either the right or the left trochanter PPD replaced every week Control group: participants acted as their own control, i.e. no dressing was applied to the opposite trochanter
Outcomes	PU incidence Outcome type: dichotomous outcome Reporting: fully reported Unit of measure: numbers Direction: lower is better Data value: endpoint Incidence of persistent erythema Outcome type: dichotomous outcome Reporting: fully reported Unit of measure: numbers Direction: lower is better Data value: endpoint
Identification	Sponsorship source: not stated Country: Japan Setting: 500‐bed geriatric hospital Comments: no comments Author's name: G Najagami Institution: Division of Health Sciences and Nursing, Graduate School of Medicine Email: not provided Address: University of Tokyo, Tokyo, Japan
Notes	PU classification system not clearly described
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded, quote: “impossible due to the type of intervention”
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not blinded, quote: "test area outlined so that the dressing applied back to the same area"
Incomplete outcome data (attrition bias) All outcomes	Low risk	ITT conducted
Selective reporting (reporting bias)	Low risk	All outcomes reported in the paper were those outlined by the study authors
Other bias	High risk	Investigators were part of the group that developed the PPD