Karcioglu 2013.

Study characteristics
Methods	Randomised, double‐blind, placebo control
Participants	N = 40, gender of participants not presented in demographic data
Interventions	Ketamine 1 mg/kg bolus IV at anaesthesia induction + 25 mcg/kg/min IV infusion until the end of surgery
Outcomes	Pain intensity (VAS) reported at PACU discharge and at 24 h postoperatively. Analgesic consumption reported as proportion (%) of participants receiving analgesics. AEs
Surgery type	Laparoscopic cholecystectomy
Group numbers after end of study (treatment/control)	17/20
Age of patient population (treatment/control)	38.6 ± 11.7 43.4 ± 12.1
Notes	No mention of sponsorship or funding. The authors declare no conflicts of interest
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random sequence
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	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	8% was withdrawn
Selective reporting (reporting bias)	Low risk	Predefined outcomes reported (three participants withdrawn from the ketamine group because of hypertension)
Size	High risk	17 and 20 participants per treatment arm