Rao 2007.

Methods	Study design: randomised controlled trial Total study duration: 3 month and one year follow‐up (one year follow‐up reported in separate paper (Rao 2010))
Participants	77 patients referred to tertiary centre for constipation and met Rome II criteria for functional constipation. Evidence of pelvic floor dyssynergia on attempted defecation 77 patients (69 female, 8 male) randomised 24 to standard therapy, 28 to biofeedback, 25 to sham biofeedback) Age ‐ mean 43 years (range 18 to 75 years) Mean symptom duration 17 years No difference in demographics between groups at baseline, but biofeedback group had 'significantly lower defecation index' and 'relatively greater pelvic floor dysfunction' (Rao 2007, p.333) than other groups at outset
Interventions	Intervention group: Manometry biofeedback: biweekly one hour sessions up to maximum of 6 over a three month period, with visual display of anal sphincter pressures during simulated defecation Also received standard advice: advice on bowel habit, diet, exercise, laxatives and fluid intake, postural and diaphragmatic breathing techniques to improve pushing efforts Comparison groups (2): Sham biofeedback: standard advice plus 6 biweekly I hour relaxation therapy sessions during a period of 3 months Manometry probe placed in rectum and practiced progressive muscle relaxation to audiotape for 20 minutes Also received intermittent balloon distension using the rectal probe to match sensory conditioning component of biofeedback
Outcomes	Subjective primary outcome measure: number of complete spontaneous bowel movements (CSBM) per week plus global satisfaction on visual analogue scale Physiological primary outcome: dyssynergic pattern of defecation and balloon expulsion time Secondary subjective outcome measures: symptom diary for 1 week: time and consistency of stool (using Bristol Stool Form Scale), straining, incomplete evacuation, digitation. Secondary objective outcomes: anorectal manometry and colonic transit study
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation sequence
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes ‐ adequate concealment
Blinding (performance bias and detection bias) All outcomes	High risk	Not blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	High attrition (n = 12 from 77), but performed intention‐to‐treat analysis at 3 months. From 52 patients randomised to biofeedback or standard care, data from 20 are reported at one year
Selective reporting (reporting bias)	Low risk	Registered on clinical trials registry
Other bias	High risk	The two groups were not equal at baseline as the biofeedback group had a significantly lower defecation index and relatively greater pelvic floor dysfunction than the sham group