Lee MJ 2015.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Control (group C) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 36 Received treatment (n): NA Analysed (n): 36 Age (mean ± SD, median (IQR), median (range)): 52.4 ± 8.3 Weight (mean ± SD, median (IQR), median (range)): 60.1 ± 4.6 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 86.11 Non‐smoker (%): 92 History of PONV/motion sickness (%): 11/0 Type of general anaesthesia: balanced anaesthesia (desflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 140.2 Use of perioperative opioids (if yes, which?): remifentanil Type of surgery: thyroid surgery Ramosetron (group R) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 36 Received treatment (n): NA Analysed (n): 36 Age (mean ± SD, median (IQR), median (range)): 53.0 ± 8.2 Weight (mean ± SD, median (IQR), median (range)): 58.84 ± 6.4 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 88.89 Non‐smoker (%): 94 History of PONV/motion sickness (%): 8/0 Type of general anaesthesia: balanced anaesthesia (desflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 143.5 Use of perioperative opioids (if yes, which?): remifentanil Type of surgery: thyroid Ramosetron + dexamethasone (group RD) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 36 Received treatment (n): NA Analysed (n): 36 Age (mean ± SD, median (IQR), median (range)): 54.3 ± 7.7 Weight (mean ± SD, median (IQR), median (range)): 60.5 ± 5.3 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 83.33 Non‐smoker (%): 94 History of PONV/motion sickness (%): 11/0 Type of general anaesthesia: balanced anaesthesia (desflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 141.5 Use of perioperative opioids (if yes, which?): remifentanil Type of surgery: thyroid Included criteria: elective thyroid surgery, between 20 and 65 years of age, ASA I or II Excluded criteria: history of allergy to any drugs used in the study, gastrointestinal disease, motion sickness, diabetes mellitus, obesity (body mass index ≥ 35 kg/m²), renal or hepatic functional impairment, pregnancy, menstruation, use of antiemetic drugs or a systemic steroid 24 hours before surgery, chronic pain disorder Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of PONV): no; (history of motion sickness, perioperative opioids): unclear
Interventions	Intervention characteristics Control (group C) Dose: NaCl Time point of administration: immediately after induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV Ramosetron (group R) Dose: 0.3 Time point of administration: immediately after induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV Ramosetron + dexamethasone (group RD) Dose: ramosetron 0.3 mg, dexamethasone 5 mg Time point of administration: immediately after induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV
Outcomes	Headache (0 to 48 hours) Outcome type: dichotomous outcome Sedation/drowsiness (0 to 48 hours) Outcome type: dichotomous outcome Adverse events (general notes in the publication, 48 hours' observation) Outcome type: general notes on side effects
Identification	Sponsorship source: NA Country: Korea Setting: inpatient, NA Author's name: Cheol Lee Institution: Department of Anesthesiology and Pain Medicine, Wonkwang University College of Medicine, Iksan, Korea Email: ironyii@wku.ac.kr Address: Department of Anesthesiology and Pain Medicine, Wonkwang University College of Medicine, 344‐2, Sinyong‐dong, Iksan 570‐711, Korea Duration of study: NA Language: English Study's primary outcome: incidence of nausea, vomiting, and rescue antiemetic drug use within 48 hours postoperatively Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "were randomly (envelope randomization) allocated to three groups" Judgement comment: no further information on sequence generation provided
Allocation concealment (selection bias)	Unclear risk	Quote: "(envelope randomization)" Judgement comment: not stated; "sequentially numbered, opaque, and sealed envelopes" (SNOSE)
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "all patients, investigators collecting the postoperative data, and nurses involved in the post‐operative care of patients were blinded to the randomization" Judgement comment: no information on blinding of anaesthesiologists provided
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "investigators collecting the postoperative data, and nurses involved in the post‐operative care of patients were blinded to the randomization"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Judgement comment: no missing outcome data
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Quote: "patient characteristics including the history of PONV, tympanic temperature, as well as operative data were similar among the groups (Table 1)" Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of PONV): no; (history of motion sickness, perioperative opioids): unclear