Mahran 2015.

Study characteristics
Methods	Randomised, double‐blind, placebo control
Participants	N = 90, of whom 60 participants in IV ketamine and control treatment arms. 100% women
Interventions	Ketamine 0.5 mg/kg bolus IV before anaesthesia induction + intraoperative IV infusion 0.25 mg/kg/h till the end of skin closure
Outcomes	Pain intensity (VAS) reported at 30 min, 2, 4, 6, 12 and 24 h postoperatively. Cumulative analgesic consumption at 24 h. AEs
Surgery type	Breast cancer surgery (radical mastectomy)
Group numbers after end of study (treatment/control)	30/30
Age of patient population (treatment/control)	53.1 ± 6.2 53.9 ± 8.1
Notes	No mention of sponsorship or funding
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random number assignment
Allocation concealment (selection bias)	Low risk	Allocation concealed in sequentially numbered, opaque envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinded personnel
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded personnel
Incomplete outcome data (attrition bias) All outcomes	Low risk	No withdrawals
Selective reporting (reporting bias)	Low risk	All predefined dropouts reported
Size	High risk	30 participants per treatment arm