Buggy 2002.

Methods	RCT Approved by the ethics committee and written informed consent obtained Setting: United Kingdom Funding: charity
Participants	Patients (20 to 80 years) having extensive abdominal or pelvic surgery involving a midline abdominal incision (open colon or rectal excision, radical gastrectomy or nephrectomy, total abdominal hysterectomy with bilateral salpingo‐oophorectomy, ovarian cystectomy)
Interventions	Treatment group: PCEA (TEA or LEA) with bupivacaine 0.125% and fentanyl 4 mcg/mL for 24 hours (n = 16) Control group: IV PCA with morphine (n = 16) All participants received general anaesthesia
Outcomes	VAS at rest at 24 hours VAS on movement at 24 hours
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Each participant was randomly assigned to 1 of 2 groups via blocked randomization from a table of random numbers
Allocation concealment (selection bias)	Low risk	Assignments were kept in sealed, sequentially numbered envelopes until use
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	"Patients were not told whether their patient controlled analgesia system was epidural or intravenous." Participants in the morphine PCA group were positioned for epidural anaesthesia but received skin infiltration of local anaesthetic only, and had an epidural catheter attached along their back with adhesive tape, as a placebo mock epidural. "Anesthetists directly caring for the patients during surgery were, of course, aware of the group allocation, but they took no part in subsequent data collection. Investigators collecting postoperative data were also aware of group allocation, but patients were blind"
Blinding of outcome assessment (detection bias) All outcomes	High risk	"Anesthetists directly caring for the patients during surgery were, of course, aware of the group allocation, but they took no part in subsequent data collection. Investigators collecting postoperative data were also aware of group allocation, but patients were blind"
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants accounted for
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Low risk	Groups well balanced The sole epidural participant who required intravenous PCA received it 6 hours postoperatively, but this participant's data were treated as from the epidural group, consistent with intention‐to‐treat analysis