Watters 1993.

Methods	RCT Approved by the research ethics committee and informed written consent obtained from each participant Setting: Canada Funding: governmental
Participants	20 consecutive adult patients of either sex who were scheduled to undergo elective colorectal resection
Interventions	Treatment group: LEA (lower lumbar level) with 2% lidocaine and epinephrine 5 mcg/mL intraoperatively only and epidural morphine after surgery (n = 12) Control group: IV/IM morphine/meperidine (n = 8) General anaesthesia for all participants
Outcomes	VAS scores (unspecified, taken as at rest) at 6, 24 and 48 hours
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Sealed envelopes prepared from a table of random numbers"
Allocation concealment (selection bias)	Low risk	"Sealed envelopes prepared from a table of random numbers"
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 "All epidural catheters were judged clinically by the attending anaesthetist to be functioning well"
Selective reporting (reporting bias)	Low risk	All results provided
Other bias	Low risk	Groups well balanced