Yoon 2009.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Ondansetron (group O) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 35 Received treatment (n): NA Analysed (n): 35 Age (mean ± SD, median (IQR), median (range)): 51 ± 4.8 Weight (mean ± SD, median (IQR), median (range)): 57.1 ± 5.3 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 60 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: balanced anaesthesia (sevoflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 266.9 Use of perioperative opioids (if yes, which?): intraoperative remifentanil Type of surgery: mastoidectomy, tympanoplasty Ramosetron (group R) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 35 Received treatment (n): NA Analysed (n): 35 Age (mean ± SD, median (IQR), median (range)): 51.43 ± 6.1 Weight (mean ± SD, median (IQR), median (range)): 57.7 ± 7.5 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 57.1 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: balanced anaesthesia (sevoflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 263.2 Use of perioperative opioids (if yes, which?): intraoperative remifentanil Type of surgery: mastoidectomy, tympanoplasty Included criteria: either sex, ASA I and II, scheduled middle ear surgery (mastoidectomy and tympanoplasty) under general anaesthesia with sevoflurane and remifentanil, 30 to 65 years of age Excluded criteria: cardiovascular, respiratory, brain, renal, hepatic disease; pregnant women; severe obesity; usual vomiting or motion sickness; nausea or vomiting within 24 hours before surgery Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of motion sickness): no; (history of PONV, non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Ondansetron (group O) Dose: 4 mg Time point of administration: before end of operation Route of administration: IV Rescue antiemetics (if yes, which?): (0%) 10 mg metoclopramide Ramosetron (group R) Dose: 0.3 mg Time point of administration: before end of operation Route of administration: IV Rescue antiemetics (if yes, which?): (0%) 10 mg metoclopramide
Outcomes	Vomiting (0 to 6 hours) Outcome type: dichotomous outcome Vomiting (6 to 24 hours) Outcome type: dichotomous outcome Headache (0 to 48 hours) Outcome type: dichotomous outcome Constipation (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, 24 hours' observation) Outcome type: general notes on side effects
Identification	Sponsorship source: NA Country: South Korea Setting: inpatient, single‐centre Author's name: Sang Ho Jung Institution: Department of Anesthesiology and Pain Medicine, Maryknoll Hospital Email: inature7@naver.com Address: Maryknoll Hospital, Daecheong‐dong 4ga, Jung‐gu, Busan 600‐730, Korea Duration of study: NA Language: Korean (Google Translator) Study's primary outcome: incidence of PONV Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Judgement comment: quote: "randomly assigned". No further information on sequence generation provided
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Judgement comment: insufficient information on blinding ("double‐blinded")
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Judgement comment: quote: "an anesthesiologist who did not know the patient's group visited the patient for 6 hours, 6‐24 hours, and 24‐48 hours postoperatively"
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	Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of motion sickness): no; (history of PONV, non‐smoker, perioperative opioids): unclear