Schricker 2002.

Methods	RCT Approved by the ethics committee and informed consent obtained Setting: Canada Funding: charity
Participants	16 patients with localized colorectal carcinoma scheduled for elective colorectal surgery None of the patients suffered from cardiac, hepatic, renal or metabolic disease
Interventions	Treatment group: thoracic epidural anaesthesia/analgesia (T10‐T12) with bupivacaine 0.5% for a sensory level from T4 to S5 before surgery, bupivacaine 0.25% during surgery and bupivacaine 0.1% with fentanyl 2 mcg/mL after surgery (n = 8). Exact duration unspecified Control group: IV PCA with morphine (n = 8) All participants also received general anaesthesia
Outcomes	Pain scores at rest at 24 hours
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"The patients were allocated according to a computer‐generated randomization schedule"
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	1 participant in the opioid group had to be excluded from further analysis because he inadvertently did not receive amino acids (because of an error made by pharmacy preparing the feeding solutions)
Selective reporting (reporting bias)	Low risk	All results provided
Other bias	Unclear risk	Groups well balanced No cross‐over mentioned Not in intention‐to‐treat