Polak 2017.

Methods	Design: 6‐week prospective, parallel‐group, randomised controlled study
Participants	Health condition: elderly people with chronic pressure ulcers Sample size: Randomisation: at participant level (more than 1 ulcer for some participants)§ Randomised (participants, n; ulcers, n): 63; not reported Experimental 1: 23; not reported Experimental 2: 20; not reported Control: 20; not reported Analysed (participants, n; ulcers, n): 63; not reported Experimental 1: 23; not reported Experimental 2: 20; not reported Control: 20; not reported Setting, country: nursing and care centre (number of sites: 3), Poland Inclusion criteria: stage II, III and IV pressure ulcers of at least 0.5 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 medical conditions impeding wound healing participants with cancer, electronic implants, malignancy, tunnelling, necrotic wound likely to involve osteomyelitis and in need of surgical intervention Characteristics of pressure ulcer: Experimental 1 Ulcer duration, mean (SD): 2.4 months (1.7) Ulcer location (n): sacrum (11), greater trochanter (8), ischial tuberosity (4) Ulcer stage (n): stage II (12), stage III (9), stage IV (2) Experimental 2 Ulcer duration, mean (SD): 2.7 months (2.2) Ulcer location (n): sacrum (13), greater trochanter (4), ischial tuberosity (3) Ulcer stage (n): stage II (11), stage III (6), stage IV (3) Control Ulcer duration, mean (SD): 3.0 months (2.2) Ulcer location (n): sacrum (13), greater trochanter (4), ischial tuberosity (3) Ulcer stage, (n): stage II (13), stage III (6), stage IV (1) Mean age (SD): Experimental group 1: 79 years (8) Experimental group 2: 80 years (11) Control group: 78 years (12) Gender: Experimental group 1: 26% male Experimental group 2: 10% male Control group: 15% male §It is clearly stated that in participant with multiple pressure ulcer, all wounds were treated but only one pressure ulcer per participant was analysed.
Interventions	Total groups in this study: three Experimental 1: cathodal ES group plus standard wound care (CG group) 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 the healthy skin 20 cm away from ulcer Device, manufacturer: Intelect Advanced Combo unit (Chattanooga, Tennessee USA) Intensity of ES: sensory perception Frequency: 100 Hz Type of current: pulsed Polarity: cathode over the ulcer for entire duration of the study Experimental 2: cathodal and anodal ES group plus standard wound care (CAG group) 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 the healthy skin 20 cm away from ulcer Device, manufacturer: Intelect Advanced Combo unit (Chattanooga, Tennessee 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 Control: placebo ES group current plus standard wound care (PG group) Same settings and duration as Experimental 1 but without current Standard wound care 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 closed (expressed as numbers) Complications/adverse events ‐ adverse event (expressed in descriptive format) Rate of pressure ulcer healing ‐ percentage area reduction (expressed as percentage per 6 week)* Not useable data§: presented as [name of outcome in review]‐ [name of outcome in study] Time to complete healing ‐ speed of wound closure (expressed as Figure) Time point included in this review: week 6 (end of intervention) * converted from percentage per 6 week to percentage per week § data are not extractable and therefore not comparable
Notes	Withdrawals, (n; reason): Experimental 1: 1; died Experimental 2: 2; health deteriorated, 2; died Control: 2; health deteriorated Funding source: all research activities were funded by the Academy of Physical Education, Poland Registry or published protocol: prospectively registered at Australian New Zealand Clinical Trials Registry (identifier ANZCTRN12614000992606)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “….in the trial generated 4 blocks of 6 letters (combinations of A, B, and C) using computer software.” p779
Allocation concealment (selection bias)	Low risk	Quote: “To conceal the allocation sequence, consecutively numbered, opaque, and sealed envelopes were used.” p779
Blinding of participants (performance bias) All outcomes	Low risk	Quote: “All patients, medical personnel, and re­searchers were blinded.” p779
Blinding of personnel (performance bias) All outcomes	High risk	Quote: “All patients….were blinded. The exception was the main investigator and principal physical therapist, who set the equip­ment to apply active or sham ES.” p779
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: “The person responsible for wound surface area measurements and statistical analysis was blinded too.” p779
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: 6/63 (10%) dropouts
Selective reporting (reporting bias)	Low risk	Comment: all pre stated outcomes were reported
Other bias	Low risk	Comment: appears free of other bias