Feeder 1991.

Methods	Design: 4‐week randomised, double‐blinded, multicentred study
Participants	Health condition: elderly people with chronic dermal ulcers Sample size: Randomisation: at participant level (more than one ulcer for some participants)§ Randomised (participants, n; ulcers, n): 59; 67 Experimental: not reported; not reported Control: not reported; not reported Analysed (participants, n; ulcers, n): 47; 50 Experimental: not reported; 26 Control: not reported; 24 Setting, country: hospital and medical centres (9 sites), USA Inclusion criteria: participants with stage II, III or IV chronic dermal ulcers (NPUAP scoring system) ulcers between 4 cm2 and 100 cm2 ulcers caused by vascular insufficiency, trauma or surgery no age or gender restrictions Exclusion criteria: ulcers completely occluded by eschars ulcers of haemorrhagic or cancerous aetiology participants with cardiac pacemakers, peripheral vascular disease, or active osteomyelitis pregnancy participants receiving radiation therapy, steroid therapy, or chemotherapy Characteristics of pressure ulcer: Experimental Ulcer etiology (%): pressure sore (65), surgical (23), traumatic (12) Ulcer duration: less than 1 month up to 12 months Ulcer location (n): ischium (8), sacrum (4), leg and foot (10), others (4) Ulcer stage (n): stage III (22), stage IV (4) Control group Ulcer etiology (%): pressure sore (75), surgical (13), vascular (4), traumatic (8) Ulcer duration: less than 1 month up to 12 months Ulcer location (n): ischium (6), sacrum (9), leg and foot (7), others (2) Ulcer stage (n): stage II (2), stage III (17), stage IV (5) Mean age (SD; range): Overall: 64 years (18; 29‐91) Experimental: 67 years (16; 29‐91) Control: 61 years (19; 30‐90) Gender: Overall: 52% male Experimental: 54% male Control: 50% 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: two Experimental: monophasic pulsed ES plus cointervention Duration: 30 minutes per session; 2 sessions per day (4 to 8 hours between sessions); 7 days per week; total 4 weeks Electrode placement: one over the ulcer and other 12 inches away from the ulcer Device, manufacturer: Vara/Pulse Stimulator, Staodynamic Inc. USA Intensity of ES: not reported Frequency: 64 Hz and 128 Hz Type of current: pulsed Polarity: altered daily until the ulcer healed Control: sham ES Same settings and duration as experimental group but without current
Outcomes	Outcomes included in this review: presented as [name of outcome in review] – [name of outcome in study] Proportion of pressure ulcers healed‐ ulcer healed (expressed as numbers) Surface area of pressure ulcers‐ area of pressure ulcer (expressed as cm2) Complications/adverse events‐ adverse events (expressed as percentage) Rate of pressure ulcer healing‐ healing rate (expressed as percentage per week) Not useable data: presented as [name of outcome in review]‐ [name of outcome in study] Time to complete healing‐ healing of ulcer (expressed in weeks)* Time point included in this review: week 4 Other time points: baseline, week 1, week 2, week 3 and until healed (end of intervention) *Included but not analysed because there were zero events in the treatment group; therefore, it is not possible to estimate the hazard ratio
Notes	Withdrawals, (n; reason): Experimental and Control: 4; did not complete the 4‐week study, 4; did not meet the eligibility criteria$, 3; uninterpretable measurements, 6; omitted or incorrect treatment Funding source: no information about funding source provided Trial registration or published protocol: no information about trial registration or published protocol provided $Authors stated that 4 participants were excluded because they did not meet the eligibility criteria but it is not clear if these participants had been randomised
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "...a randomisation list was established for each center by the central study director. Each consecutive numbered patient at each center was then randomly assigned to either a treatment group, which used an active stimulator, or a control group, which used a stimulator that had been modified to produce no output current." p642 Comment: insufficient detail reported
Allocation concealment (selection bias)	Unclear risk	Quote: "Each consecutive numbered patient at each center was then randomly assigned to either a treatment group, which used an active stimulator, or a control group, which used a stimulator that had been modified to produce no output current." p642 Comment: insufficient detail reported
Blinding of participants (performance bias) All outcomes	Low risk	Quote: "Neither the ….. nor the patients were aware of which type of device was used for a particular wound during the 4‐week study period." p642 Comment: control participants received sham treatment
Blinding of personnel (performance bias) All outcomes	Low risk	Quote: "The clinical investigators did not have access to the randomisation lists and therefore did not know whether a particular device was active or inactive." p642 Quote: "Neither the investigators nor … were aware of which type of device was used for a particular wound during the 4‐week study period." p642 Comment: it is implied that the clinical investigators (personnel) administered the treatment and therefore were blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "To further ensure that the clinical trials were blinded, the persons who administered the treatments were different from those who obtained the measurements." p643
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: under heading "Subject"; p641 Comment: 17/67 (25%) dropouts
Selective reporting (reporting bias)	High risk	Comment: only reports wound size but indicate that wound appearance was also recorded each week. This is not reported. Comment: not stated that data will be presented as percentage change area
Other bias	High risk	Comment: Mix of a within‐ and between‐participants design. In participants with two wounds the unit of randomisation was the wound. It is not clear whether the analyses took into account the paired nature of the within‐participant data. Control group participants were moved across to the experimental group after 4 weeks and all staff unblinded. 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.