Altintas 2000.

Methods	Prospective double‐blinded randomized controlled trial
Participants	70 patients aged 17 to 60 years, American Society of Anesthesiologists (ASA) class1 and class 2, who were to undergo plastic surgery
Interventions	10% lidocaine to inflate the endotracheal tube (ETT) cuff Saline to inflate the ETT cuff
Outcomes	Sore throat Severity of sore throat (visual analogue scale of intensity of sore throat: 0 to 100 mm) Bucking on extubation Plasma lidocaine concentrations
Notes	Topical lidocaine therapy Muscle relaxants used
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The information on sequence generation is not described. Insufficient information about the sequence generation process to permit judgement of 'Yes' or 'No'.
Allocation concealment (selection bias)	Unclear risk	The information on allocation is not described. Insufficient information about the sequence generation process to permit judgement of 'Yes' or 'No'.
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "Patients were asked about the presence of sore throat by the same anaesthesiologist". The "anaesthesiologist" means "anaesthesiologist who was unaware of the nature of the fluid in the cuff". The patient was anaesthetized and therefore blinded to the intervention. There is no description about double‐blinding.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	The information on incomplete outcome reporting is not described. Insufficient information about the incomplete outcome data.
Selective reporting (reporting bias)	Unclear risk	There is no information about selective reporting.
Other bias	Unclear risk	There is no apparent description of other bias.