Polak 2016b.

Methods	Design: 6‐week prospective, parallel‐group, randomised controlled study
Participants	Health condition: elderly people with pressure ulcers Sample size: Randomisation: at participant level (more than one ulcer for some participants)§ Randomised (participants, n; ulcers, n): 60; not reported Experimental: 30; not reported Control: 30; not reported Analysed (participants, n; ulcers, n): 52; 60 Experimental: 24; 29 Control: 28; 31 Setting, country: residential care centre and temporary care facilities (number of sites: not reported), Poland Inclusion criteria: stage II, III and IV pressure ulcers between 1 cm2 and 50 cm2 (NPUAP classification) older adults (60 years or more) with high risk of pressure ulcer development (< 14 points on Norton scale) duration of pressure ulcers between 1 and 12 months Exclusion criteria: participants with poor health participants with a deep, tunnelling, necrotic wound likely to involve osteomyelitis and in need of surgical intervention participants with venous insufficiency, neoplastic disease and/or diabetes Characteristics of pressure ulcer: Experimental Ulcer duration, mean (SD): 2.6 months (2.8) Ulcer location, (n): buttock region (25), lower extremity (3), trunk (1) Ulcer stage, (n): stage II (19), stage III (7), stage IV (3) Control Ulcer duration, mean (SD): 2.5 months (2.4) Ulcer location, (n): buttock region (25), lower extremity (5), elbow (1) Ulcer stage, (n): stage II (23), stage III (7), stage IV (1) Mean age (SD): Experimental group: 80 years (10) Control group: 79 years (10) Gender: Overall: 17% male Experimental group: 21% male Control group: 14% male §It is not clearly stated whether participants or pressure ulcers were randomised but the number of pressure ulcers is greater than the number of participants. We have assumed that randomisation was at the participant level.
Interventions	Total groups in this study: three Experimental 1: ES group (ES plusstandard wound care) Duration: 50 minutes per session; 1 session per day; 5 days a week; total 6 weeks Electrode placement: one over the ulcer and the other on healthy skin 20 cm away from ulcer Device, manufacturer: Intelect Advanced device (Model 2771, Chattanooga Group, California USA) Intensity of ES: sensory perception Frequency: 100 Hz Type of current: pulsed Polarity: cathode over the ulcer for first 5 days and then anode over the ulcer for entire duration of the study Experimental 2: ultrasound group (US plusstandard wound care) This group is not included in this review Control group: standard wound care This included pressure ulcer prevention measures, wound care and physical treatment advocated by interdisciplinary medical team
Outcomes	Outcomes included in this review: presented as [name of outcome in review]‐ [name of outcome in study] Surface area of pressure ulcer ‐ wound surface area (expressed in cm2) Proportion of pressure ulcers healed ‐ pressure ulcers healed (expressed as numbers) Complications/adverse events ‐ adverse event (expressed in descriptive format) Rate of pressure ulcer healing ‐ healing rate (expressed as percentage per 6 week)* Time point included in this review: week 6 (end of intervention) Other time point: baseline, week 4 * converted from percentage per 6 week to percentage per week
Notes	Withdrawals, (n; reason): Experimental 1: 4; health deteriorated and declined to participate, 2; died Control: 1; health deteriorated and declined to participate, 1; died Funding source: all research activities were funded by the Academy of Physical Education, Poland Registry or published protocol: retrospectively registered at Australian New Zealand Clinical Trials Registry (identifier ANZCTR12613001374752)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Patient allocation to groups was performed disregarding when and who would deliver the treatment.” p746
Allocation concealment (selection bias)	Low risk	Quote: “The allocation sequence was concealed by using sealed envelopes with consecutive numbers.” P746
Blinding of participants (performance bias) All outcomes	High risk	Quote: “……is that patients were not blinded and that control groups with sham ES and sham US were not created;” p753
Blinding of personnel (performance bias) All outcomes	High risk	Quote: “…..the main investigator opened the envelopes one at a time in the presence of the principal physiotherapist and the particular patient was directed to the indicated group.” p746
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: “WSA was determined and the statistical analysis was performed blinded.” p749 Comment: not clearly stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: 8/60 (13%) dropouts
Selective reporting (reporting bias)	Low risk	Comment: all pre stated outcomes were reported
Other bias	High risk	Comment: the unit of randomisation was the participant but some participants had more than one pressure ulcer and data were analysed by pressure ulcers with no account for non‐independence of data