Griffin 1991.

Methods	Design: 20‐day double‐blinded randomised controlled study
Participants	Health condition: people with spinal cord injury Sample size: Randomisation: at participant level (one ulcer per participant)§ Randomised (participants, n; ulcers, n): 20; 20 Experimental: 10; 10 Control: 10; 10 Analysed (participants, n; ulcers, n): 17; 17 Experimental: 8; 8 Control: 9; 9 Setting, country: Spinal Cord Injury Service, Baptist Memorial Hospital Regional Rehabilitation Centre (1 site), USA Inclusion criteria: male participants with spinal cord injury pelvic pressure ulcers (sacral, coccygeal, gluteal or ischial regions) stage II, II or IV pressure ulcers (DeLisa classification system) Exclusion criteria: participants with severe cardiac disease, cardiac arrhythmia, uncontrolled autonomic dysreflexia or cardiac pacemaker Characteristics of pressure ulcer: Experimental Ulcer duration, median (range): 4.5 weeks (2 to 116) Ulcer location (n): gluteal/ischial (5), sacral/coccygeal (3) Ulcer stage (n): stage II (2), stage III (5), stage IV (1) Control Ulcer duration, median (range): 3.0 weeks (1 to 30) Ulcer location (n): gluteal/ ischial (1), sacral/coccygeal (8) Ulcer stage (n): stage II (2), stage III (6), stage IV (1) Median age (range): Experimental: 33 years (17 to 54) Control: 26 years (10 to 74) Gender: Overall: 100% male §It is clearly stated that participants (not pressure ulcers) were randomised.
Interventions	Total groups in this study: two Experimental: HVPC and nursing care Duration: 1 hour per day; total 20 consecutive days Electrode placement: one over the ulcer and the other (dispersive electrode) strapped to medial thigh Device, manufacturer: Intelect 500 HVPC stimulator; Chattanooga Corp. USA Intensity of ES: gradually increased (to 200 V) just below the onset of a muscle contraction Frequency: 100 Hz Type of current: direct, continuous mode frequency 100pps with total current 500 μA Polarity: negative at ulcer for 20 days Control: placebo HVPC and nursing care Same settings and duration as experimental group, but without current Nursing care for both groups Twice daily cleansing of ulcers using Cara‐Klenz followed by an application of Carrington gel and a dry dressing Ulcer debridement, whenever necessary All possible efforts were made to keep pressure off the ulcer with a routine 2‐hour appropriate turning schedule in bed Bed mattress and wheelchair cushion were not changed for any patient during the course of the study
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) Time to complete healing ‐ percentage of reduction in ulcer area (expressed as figure) Complications/adverse events ‐ adverse events (expressed in descriptive format) Rate of pressure ulcer healing ‐ percentage change (expressed as percentage per 5 days) 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: day 20 (end of intervention) Other time points: baseline, day 5, day 10 and day 15 *SD not provided
Notes	Withdrawals, (n; reason): Experimental and Control: 2; developed medical complications, 1; required surgical repair of the ulcer Funding source: high voltage pulsed direct current units loaned by the Chattanooga Corporation and digitizer for analysis of WSA was provided by WC Campbell foundation 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…" abstract, p433 Comment: insufficient detail reported
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient detail reported
Blinding of participants (performance bias) All outcomes	Low risk	Quote: "…a placebo HVPC group…" abstract Comment: control participants received placebo treatment
Blinding of personnel (performance bias) All outcomes	High risk	Quote: "All treatments were administered by one of three persons‐two physical therapists (JWG and JKC) and a nursing coordinator (RAM). The nursing staff and patients were kept blinded as to patient treatment group assignment" p436 Comment: personnel were not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "The same person (JWG) conducted all WSA measurements." p437 and "The design of future studies might also be improved by having the person conducting the measurements blinded as to ulcer treatment." p441 Comment: JWG was not blinded, p436
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Seventeen of the 20 patients completed the study. Three patients were transferred to the acute care hospital (2 patients developed medical complications, and 1 patient required surgical repair of his ulcer) and thus were eliminated from the study." p438 Comment: 3/20 (15%) dropouts
Selective reporting (reporting bias)	Low risk	Comment: all pre stated outcomes were reported
Other bias	Unclear risk	Comment: trial was sponsored by third parties who were likely to have a vested interest in a positive finding