Dinning 2015#.

Methods	Randomised crossover trial Blinding: participant and investigator. Follow‐up: 3 weeks (long‐term follow‐up not reported) Setting: two centres in Sydney, Australia. Intention‐to‐treat analysis: yes Withdrawals: 6 participants
Participants	Enrolled: 59 Median age (range): 42 (19 to 74) Gender: male (4); female (55). Duration of symptoms: constipation > 10 years (43), 5 to 10 years (7), and 2 to 5 years (9) Received permanent implant: 55 Lost to follow‐up: 2 Inclusion criteria: All of the following: i) A complete bowel movement on less than 3 days per week, for at least 2 of 3 weeks of the surveillance phase (determined from daily stool diaries). ii) Aged 18 to 75 yrs; iii) Scintigraphically confirmed slow colonic transit defined as colonic isotope retention > 20% at 96 h (laboratory upper limit of normal = 1% at 96 h; iv) Normal anorectal manometry, with no evidence of dyssynergia and confirmed ability to expel rectal balloon; v) With no radiographic evidence of functional (e.g. pelvic floor dyssynergia) or anatomical (e.g. significant rectocele with retention of contrast, occluding intussusception) impediment to the expulsion of the radio‐opaque contrast; vi) Failed symptomatic response to standard therapies including osmotic agents, faecal emollients, laxatives, dietary modification and exercise; and vii) A normal colonoscopy within 5 years Exclusion criteria: Any one of the following; i) Metabolic, neurogenic or endocrine disorder(s) known to cause constipation; ii) Drugs listing constipation as a potential side effect; or iii) Non‐English speaker or an inability to provide informed consent. Any one of the following; i) Prior abdominal radiotherapy; ii) Prior abdominal surgery (except cholecystectomy, appendicectomy, inguinal hernia repair, splenectomy, fundoplication; oophorectomy or hysterectomy); iii) Current or planned pregnancy; iv) Co‐morbidity considered to put the patient at risk from surgical electrode implantation; or v) History of malignancy.
Interventions	All participants underwent peripheral nerve evaluation. Then participants received permanent electrode implantation. Intervention: 'suprasensory' stimulation for 3 weeks Control: Sham stimulator off for 3 weeks. Wash out period: 2 weeks.
Outcomes	Bowel diary (stool frequency per week; bowel motion per week; feeling of complete evacuation per week; straining per week; laxative free days per week; soft stool per week; normal stool per week; hard stool per week; pain score weekly average; bloating score weekly average; weekly global satisfaction score; weekly bothersome score). Quality of life SF‐36.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Utilised an off‐site NHMRC clinical trials centre automated phone link.
Allocation concealment (selection bias)	Low risk	Utilised an off‐site NHMRC clinical trials centre automated phone link.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants and personnel blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Investigator blinded.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Out of the 59 participants enrolled, 6 withdrew. The reasons for discontinuation were depression (n = 1), too far to travel (n = 2), could not commit (n = 1), pregnancy (n = 1) and severe wound infection (n = 1).
Selective reporting (reporting bias)	Low risk	All outcomes reported.
Other bias	Low risk	None identified