Köse 2012.

Study characteristics
Methods	Randomised, double‐blind, placebo control
Participants	N = 150, of whom 120 participants in IV ketamine and control treatment arms. About 74% women
Interventions	Ketamine 0.1 mg/kg OR ketamine 0.25 mg/kg OR ketamine 0.5 mg/kg bolus IV 20 mins before the end of surgery. Heterogeneous surgery types
Outcomes	Pain intensity (VAS) reported at 0, 1 and 2 h postoperatively. Time to first analgesic request. AEs. Postoperative shivering
Surgery type	Various operations under general anaesthesia
Group numbers after end of study (treatment/control)	90/30
Age of patient population (treatment/control)	41.2 ± 12 44.5 ± 9.2
Notes	Primary endpoint was postoperative shivering. 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)	Low risk	Allocation in closed envelopes, identical study drug syringes prepared and labelled by an independent investigator not participating in the further study
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinded participants and personnel
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded investigator made assessments
Incomplete outcome data (attrition bias) All outcomes	Low risk	No withdrawals
Selective reporting (reporting bias)	Low risk	Predefined outcomes reported
Size	High risk	30 participants per treatment arm