Cuschieri 1985.

Methods	RCT Informed consent not mentioned Setting: United Kingdom Funding: charity
Participants	75 patients undergoing open cholecystectomy
Interventions	Treatment group: low thoracic epidural analgesia (catheters inserted after induction and loaded with an age‐related dose of bupivacaine 0.5%) followed by intermittent boluses of 0.5% bupivacaine for 12 hours followed by intramuscular morphine on request (n = 25) Control group: intermittent intramuscular on request (n = 25) or continuous intravenous morphine for 60 hours (n = 25) General anaesthesia for all participants
Outcomes	Pain: Participants receiving epidural bupivacaine for 12 hours had better analgesia than those receiving morphine (P value < 0.001)
Notes	No serious complications occurred in the epidural group Data not extractable. Study authors contacted on 18 July 2014, but did not reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomized", no details
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, "assessed daily during the postoperative period by a single observer"
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up. 4 failed attempts at catheter insertion kept as intention‐to‐treat
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Low risk	Groups well balanced