Asbjornsen 1990.

Methods	Design: 6‐week randomised placebo controlled study
Participants	Health condition: elderly people with pressure ulcers 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): 16; 16 Experimental: 7; 7 Control: 9; 9 Setting, country: Department of Geriatric Medicine (1 site), Norway Inclusion criteria: inpatients pressure ulcers on heels or sacral region Exclusion criteria: not reported Characteristics of pressure ulcer: Experimental Ulcer duration: not reported Ulcer location (n): sacrum (3), heel (4) Ulcer stage: not reported Control Ulcer duration: not reported Ulcer location (n): sacrum (2), heel (7) Ulcer stage: not reported Mean age (range): Experimental: 83 years (73‐94) Control: 83 years (73‐91) Gender: not reported §It is not clearly stated whether participants or pressure ulcers were randomised but the number of pressure ulcers equals the number of participants.
Interventions	Total groups in this study: two Experimental: TENS and conventional treatment Duration: 30 minutes per session; 2 sessions per day; 5 days per week; total 6 weeks or before (if healed) Electrode placement: one over the web space between the first and the second metacarpal bones and the other over the ulnar edge of the same hand Device, manufacturer: TENS, Deca‐Pulse Denmark Intensity of ES: gradually increased until a minimal perceptible contraction of an adjacent muscle was seen Frequency: 100 Hz Type of current: pulsed Polarity: not reported Control: placebo TENS and conventional treatment Same settings and duration as Experimental but without current. Conventional treatment for both groups This included measures to improve general health, adequate local care and avoidance of pressure.
Outcomes	Outcomes included in this review: presented as [name of outcome in review]‐ [name of outcome in study] Proportion of pressure ulcers healed‐ complete healing (expressed as numbers) Surface area of pressure ulcers‐ area of pressure ulcer (expressed as mm2)* Complications/adverse events‐ adverse events (expressed in descriptive format) Not useable data: presented as [name of outcome in review]‐ [name of outcome in study] Time to complete healing‐ healing of ulcer (expressed as Figures)** Time point included in this review: week 6 (end of intervention) Other time points: baseline and week 4 *converted to cm2 for the purpose of analyses **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: 3; early discharge from the hospital, “got tired of intervention” and leg amputation. Control: 1; dead Funding source: no information about funding source provided 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: "Those who gave consent were randomised..." p210 Comment: insufficient detail reported
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient detail reported
Blinding of participants (performance bias) All outcomes	Low risk	Quote: control participants received "placebo TENS”. p213
Blinding of personnel (performance bias) All outcomes	Unclear risk	Comment: insufficient detail reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "One of us (GA) who did not know the patients' allocation…..measured the ulcers." p211
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "Altogether, 20 patients were recruited, but 4 of these did not participate for a minimum of 4 weeks." p210 Comment: 4/20 (20%) dropouts
Selective reporting (reporting bias)	Low risk	Comment: all pre stated outcomes were reported
Other bias	Low risk	Comment: appears free of other bias