Vaizey 2000#.

Methods	Randomised crossover trial. Blinding: participant and investigator. Follow‐up: the study consisted of two 2‐week intervals with subsensory stimulation either 'on' or 'off' Setting: single centre, UK Withdrawals: none Intention‐to‐treat analysis: yes
Participants	Enrolled: 2 Age: 65 and 61 years Gender: female (2). Duration of symptoms: 2.5 years and 3 years. Inclusion criteria: passive faecal incontinence; intact external sphincter; informed consent given Exclusion criteria: not stated
Interventions	To implant the unilateral electrode (Medtronic InterStim model 3080), the sacral nerve root (usually S3) that produces the maximal anal response was identified via percutaneous needle stimulation. An incision over the sacrum allows access to the sacral foramen. The permanent electrode was inserted directly and secured to the sacral periosteum after checking its correct placement by stimulation. A connecting lead (model 7495) was then tunnelled to the anterior abdominal wall to be connected to the stimulator. The Implantable Pulse Generator (model 3023) is programmable using telemetry. The voltage required for stimulation was between 0.5 and 2 volts at a frequency of 15 pulses per second and a pulse width of 210 μs. A Intervention: stimulator 'on' for two weeks with subsensory stimulation B Control: stimulator 'off' for two weeks No treatment‐free period between the weeks
Outcomes	Episodes of faecal incontinence for liquid or solid stool; anal manometry; psychological assessment; quality of life.
Notes	Quality of life was assessed with the SF‐36 instrument, score 0 (poor) to 100 (excellent), reporting the domains of role‐emotional, general health, mental health, bodily pain, physical functioning, role‐physical, social function, and vitality.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Unclear.
Allocation concealment (selection bias)	Unclear risk	Unclear.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants and outcome assessors were blinded to the allocation.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants and outcome assessors were blinded to the allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Results were reported for everyone who entered the studies and the participants were analysed in the groups to which they were originally allocated, effectively resulting in an intention‐to‐treat analysis.
Selective reporting (reporting bias)	Unclear risk	Psychological assessment not reported in the results.
Other bias	Low risk	None identified.