Bois 1997.

Methods	RCT Approved by the institution and informed consent obtained Setting: Canada Funding: industry
Participants	124 patients scheduled for elective abdominal aortic surgery were recruited
Interventions	Treatment group: TEA (T6‐T7 or T7‐T8) with bupivacaine 0.125% and fentanyl 10 mcg/mL adjusted for VAS scores ≤ 3 for 48 hours (n = 55) Control group: IV PCA with morphine for 48 hours (n = 59) General anaesthesia for all participants
Outcomes	VAS scores at rest at 8 and 24 hours Hospital LOS (days)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"prospectively 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
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 participants with TEA and 6 with PCA were excluded because of failure of Holter monitoring or epidural analgesia, or because use of analgesia was not included in the protocol
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Unclear risk	Groups well balanced Not in intention‐to‐treat One participant was initially ascribed to the epidural group and received postoperative PCA instead because of a failed epidural (2 dural punctures during performance of the epidural). This participant was not excluded from the study