Glia 1997.

Methods	Study design: randomised controlled trial Total study duration: six month follow‐up following five week intervention
Participants	26 consecutive patients with functional constipation ‐ based on Rome I criteria ‐ organic lesions excluded Proportion of females or males not reported. Age ‐ mean 55 years (range 28 to 78 years); duration of symptoms ‐ mean 11 years (range 1 to 35 years) 10 patients had rectocele, 1 had enterocele, 11 had intussusception and 4 had rectal prolapse Baseline comparability between groups not reported
Interventions	Intervention group: Manometry Biofeedback 1 to 2 sessions per week for maximum of 10 sessions Pressure‐based training using four‐lumen catheter ‐ patients were allowed to view manometric recordings of pressure and encouraged to relax anal sphincter during balloon expulsion Comparison group: EMG biofeedback using bilateral surface electrodes, same frequency as manometry
Outcomes	Balloon expulsion test of 60 mL water filled balloon. Whole gut transit Anorectal manometry and EMG Bowel symptom diary daily for 1 week Global rating of treatment effect: worse or unaltered or better
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer randomised sequence generation
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes
Blinding (performance bias and detection bias) All outcomes	High risk	Not blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	High attrition (six participants from 26, but three from each group) and no intention‐to‐treat analysis
Selective reporting (reporting bias)	Unclear risk	Not registered on a clinical trials registry
Other bias	Unclear risk	Recruitment bias and power unclear