Kudoh 2001.

Methods	RCT Approved by the medical ethics committee and informed consent obtained from all patients and their families Setting: Japan Funding: unspecified
Participants	46 patients, ranging in age from 36 to 77 years, who were diagnosed as having schizophrenia by Diagnostic and Statistical Manual of Mental Disorders and scheduled for elective lower abdominal surgery including colectomy, hemicolectomy or sigmoidectomy for malignant tumours
Interventions	Treatment group: TEA (T9‐T10 with the catheter threaded 3 cm passed the needle tip) with bupivacaine 0.25%. A bolus was given before surgery; the infusion was started after surgery and was maintained for 72 hours (n = 23) Control group: IV 4 mcg/kg buprenorphine and continuous infusion of 0.6 mcg/kg/h buprenorphine for 96 hours (n = 23) General anaesthesia for all participants
Outcomes	VAS scores at 6, 24, 48 and 72 hours (taken as at rest) Time to first flatus (hours) Time to first faeces (hours)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization was performed via computer‐generated codes
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Low risk	Groups well balanced