Guillou 2003.

Study characteristics
Methods	Randomised, double‐blind, placebo control
Participants	N = 101, about 54% women
Interventions	Ketamine 0.5 mg/kg bolus IV after surgery + infusion 2 µg/kg/min for 24 h and 1 µg/kg/min from 24‐48 h
Outcomes	Pain intensity (VAS) at rest and during movement. Cumulative dose of PCA morphine. Outcomes reported every 4 h up to 48 h postoperatively
Surgery type	Major abdominal surgery
Group numbers after end of study (treatment/control)	41/52
Age of patient population (treatment/control)	60 ± 16 60 ± 15
Notes	No mention of sponsorship or funding
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation process not described
Allocation concealment (selection bias)	Unclear risk	Allocation concealment method not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinded personnel
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded observer
Incomplete outcome data (attrition bias) All outcomes	Low risk	8% was withdrawn
Selective reporting (reporting bias)	Low risk	Predefined outcomes reported
Size	Unclear risk	41 and 52 participants per treatment arm