Gentzkow 1991.

Methods	Design: 4‐week double‐blind placebo multicentred randomised controlled study
Participants	Health condition: people with pressure ulcers Sample size: Randomisation: at ulcer level§ Randomised (participants, n; ulcers, n): not reported; 49 Experimental: not reported; 25 Control: not reported; 24 Analysed (participants, n; ulcers, n): 37; 40 Experimental: not reported; 21 Control: not reported; 19 Setting, country: inpatient and outpatient departments (9 sites), Canada and USA Inclusion criteria: stage II, III or IV pressure ulcer (IAET staging system) pressure ulcers between 4 cm2and 100 cm2 if more than one pressure ulcer, could be on same or opposite side of the body patients who were co‐operative patients who were available for the duration of the study Exclusion criteria: pressure ulcers that were occluded by eschar, had bleeding or involved major blood vessels pressure ulcers located in presternal, periorbital or laryngeal/pharyngeal regions pregnancy patients with cardiac pacemakers, osteomyelitis, peripheral vascular disease, cancer, long‐term steroid therapy, chemotherapy, radiotherapy or obesity Characteristics of pressure ulcer: Experimental Ulcer duration (%): < 3 months (25), > 3 months (75) Ulcer location (n): hip/ischial tuberosity (9), sacrum/coccyx (4), leg (2), foot (6) Ulcer stage (n): stage III (16), stage IV (5) Control Ulcer duration (%): < 3 months (28), > 3 months (72) Ulcer location (n): hip/ischial tuberosity (6), sacrum/coccyx (8), leg (1), foot (4) Ulcer stage (n): stage II (1), stage III (14), stage IV (4) Mean age (SD): Overall: 63 years (18) Experimental: 63 years (18) Control: 62 years (18) Gender: Experimental: 61.9% male Control: 47.4% male §It is clearly stated that pressure ulcers (not participants) were randomised.
Interventions	Total groups in this study: two Experimental: STIM and conventional care Duration: 30 minutes per session; 2 sessions per day; 7 days per week; total 4 weeks Electrode placement: one over the ulcer and the other over a large muscle group at least 12 inches from the ulcer Device, manufacturer: Dermapulse Stimulator; manufacturer‐ not reported Intensity of ES: not reported Frequency: 64 Hz and 128 Hz Type of current: pulsed Polarity: negative changed every 3 days until the ulcer debrided and serosanguinous drainage appeared then changed every day when ulcer progressed to stage 2 until healed Control: shamand conventional care Same settings and duration as experimental group but without current Conventional care for both groups Care prescribed by the physician individualised to the needs of the patient. In all patients, wounds were kept hydrated with saline moistened gauze between treatments.
Outcomes	Outcomes included in this review: presented as [name of outcome in review]‐ [name of outcome in study] Complications/adverse events ‐ adverse event (expressed as numbers) Rate of pressure ulcer healing ‐ percentage of ulcer healed (expressed as percentage per week) Not useable data: presented as [name of outcome in review]‐ [name of outcome in study] Surface area of pressure ulcers‐ wound surface area (expressed as mm2)* Time point included in this review: week 4 (end of intervention) Other time points: baseline, week 1, week 2 and week 3 *SD not provided for the postdata
Notes	Withdrawals, (n; reason): Experimental and Control‐ 6; received less than 4 weeks treatment, 3; serious protocol violations Funding source: this study was supported by a grant from Staodyn, Inc. Gentzkow (first author) was the Vice President and Medical Director of Staodyn, Inc. Trial registration or published protocol: no information about trial registration or published protocol provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Randomly assigned…." p160 Comment: insufficient detail reported
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient detail reported
Blinding of participants (performance bias) All outcomes	Low risk	Quote: "Sham device…..[and the]….patients were unaware of whether the device was active or sham, and all study procedures were identical for both groups." p160 Comment: control participants received sham treatment
Blinding of personnel (performance bias) All outcomes	Low risk	Quote: "Investigators….were unaware of whether the device was active or sham, and all study procedures were identical for both groups." p160 Comment: personnel were blinded to the treatment group
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "Investigators and patients were unaware of whether the device was active or sham, and all study procedures were identical for both groups." p160 Comment: insufficient detail reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "Overall, 40/49 ulcers (19 sham, 21 stim) or 81.6% were included in the analysis. These 40 ulcers were on 37 patients; three patients each had two ulcers included in the analysis." p164 Comment: 9/49 (18%) dropouts
Selective reporting (reporting bias)	Low risk	Comment: all pre stated outcomes were reported
Other bias	High risk	Comment: Trial was sponsored by a third party who was likely to have a vested interest in a positive finding. One of the authors (GDG) was the Vice President and Medical Director of Staodyn, Inc. (medical equipment company). The unit of randomisation was the pressure ulcer and data were analysed by pressure ulcers with no account for non‐independence of data.