Choi 2016.

Methods	Placebo‐controlled, RCT Sequence generation not described Follow‐up for 3 months
Participants	Participants: 84 adults in a university setting in Korea Operation: robot‐assisted thyroidectomy 2 groups, size: 41/43 Age (± SD), group 1, 2: not described Men/women, group 1, 2: not described Exclusion criteria: not described
Interventions	Group 1 (lidocaine): after induction of anaesthesia, participants received a bolus of 2 mg/kg of lidocaine intravenously followed by continuous infusion at a rate of 3 mg/kg/h during surgery. Further details of anaesthetic regimen were not provided. Group 2 (control): same as above except 0.9% saline was substituted for lidocaine. Adjuvants: none Immediate post‐op pain control: no improvement
Outcomes	Dichotomous: pain vs no pain Continuous: none Other reported: quality of recovery and pain scores during 24 h and 48 h postoperatively
Notes	Study published only as an abstract. We were unable to obtain additional information about methods, randomization or blinding methods from the study author. Funding sources: funding of study not described Conflicts of interest: conflicts of interest statement not provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Patients were "randomly allocated" but no further description of sequence generation was included
Allocation concealment (selection bias)	Unclear risk	Concealment of allocation not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding of participants and personnel not described
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of outcome assessors not described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Degree of attrition not described
Selective reporting (reporting bias)	Unclear risk	Use of subgroup analysis not described
Null bias	High risk	Quote: "pain scores for 2 days after surgery were not different between the two groups."