Elkaradawy 2011.

Methods	RCT Approved by the ethics committee and informed consent obtained Setting: Egypt Funding: unspecified
Participants	50 ASA 2 type 2 diabetic patients undergoing open cholecystectomy with negative stress exercise test and at least 2 cardiac risk factors preoperatively Exclusion criteria were history of coronary heart disease; hypertension; respiratory, renal or hepatic insufficiency; or contraindication to epidural analgesia
Interventions	Treatment group: thoracic (T7‐T8 and advanced 3 cm) epidural analgesia with 15 mL of 0.2% ropivacaine and fentanyl 2 mcg/mL followed by 5 to 8 mL/h of 0.1% ropivacaine plus fentanyl 1 mcg/mL at 5 to 8 mL/h for 24 hours (n = 25) Control group: IV patient‐controlled analgesia with morphine (n = 25) General anaesthesia for all participants
Outcomes	Pain: less pain with epidural analgesia
Notes	Results not extractable. Study authors contacted on 15 June 2014, but did not reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"block‐wise balanced randomization"
Allocation concealment (selection bias)	Low risk	"on cards sealed into opaque envelopes", "opened after taking decision to operate"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"neutral observer blinded with anaesthetic and analgesic techniques"
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up
Selective reporting (reporting bias)	Low risk	All results provided
Other bias	Low risk	Groups well balanced