Sahin 2004.

Study characteristics
Methods	Randomised, double‐blind, placebo control
Participants	N = 47, of whom 33 participants in IV ketamine and control treatment arms. About 52% women
Interventions	Pre‐incisional ketamine 0.5 mg/kg bolus IV
Outcomes	Pain intensity (VAS), reported in 15‐min intervals during the 1st h. Cumulative analgesic consumption reported at 24 h postoperatively. Time to first analgesic request. AEs
Surgery type	Lumbar discectomy
Group numbers after end of study (treatment/control)	17/16
Age of patient population (treatment/control)	46.5 ± 7.3 48.3 ± 11.2
Notes	3 study groups. The treatment group received ketamine bolus IV + remifentanil intraoperatively. The 2nd group where participants received saline bolus IV + remifentanil intraoperatively served as a control group. The 3rd group (14 participants) received saline bolus IV + saline infusion intraoperatively and was excluded from the analysis. 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 personnel
Incomplete outcome data (attrition bias) All outcomes	Low risk	No withdrawals
Selective reporting (reporting bias)	Unclear risk	Predefined outcomes reported but misses exact numbers of PONV, only mentioned that the incidences of nausea, vomiting were similar among groups
Size	High risk	17 and 16 participants per treatment arm