Akin 2005.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Tropisetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 35 Received treatment (n): NA Analysed (n): 35 Age (mean ± SD, median (IQR), median (range)): 34.4 ± 10 Weight (mean ± SD, median (IQR), median (range)): 73.3 ± 12.9 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 57.14 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (N₂O, desflurane) Duration of anaesthesia or surgery (in min; as mean or median): 181 Use of perioperative opioids (if yes, which?): 1 µg/kg fentanyl for induction Type of surgery: tympanomastoid surgery Tropisetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 35 Received treatment (n): NA Analysed (n): 35 Age (mean ± SD, median (IQR), median (range)): 33.2 ± 13.8 Weight (mean ± SD, median (IQR), median (range)): 67 ± 10 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 Type of general anaesthesia: inhalational anaesthesia (N₂O, desflurane) Duration of anaesthesia or surgery (in min; as mean or median): 173 Use of perioperative opioids (if yes, which?): 1 µg/kg fentanyl for induction Type of surgery: tympanomastoid surgery Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 35 Received treatment (n): NA Analysed (n): 35 Age (mean ± SD, median (IQR), median (range)): 31.2 ± 12.7 Weight (mean ± SD, median (IQR), median (range)): 73.3 ± 14.6 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 57.14 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (N₂O, desflurane) Duration of anaesthesia or surgery (in min; as mean or median): 165 Use of perioperative opioids (if yes, which?): 1 µg/kg fentanyl for induction Type of surgery: tympanomastoid surgery Included criteria: ASA I and II, 18 to 65 years of age, scheduled for elective tympanomastoid surgery Excluded criteria: gastrointestinal disorders, intake of antiemetics or centrally acting medication within 24 hours before surgery, menstruation, body weight exceeding optimal weight > 50%, therapy with corticosteroids or immunosuppressives Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, perioperative opioids): no; (history of PONV/motion sickness, non‐smoker): unclear
Interventions	Intervention characteristics Tropisetron Dose: 5 mg Time point of administration: at induction Route of administration: IV Rescue antiemetics (if yes, which?): 11.4% (metoclopramide 10 mg IV) Tropisetron + dexamethasone Dose: tropisetron 5 mg, dexamethasone 5 mg Time point of administration: at induction Route of administration: IV Rescue antiemetics (if yes, which?): 8.6% (metoclopramide 10 mg IV) placebo Dose: NaCl Time point of administration: at induction Route of administration: IV Rescue antiemetics (if yes, which?): 40% (metoclopramide 10 mg IV)
Outcomes	PONV (0 to 24 hours) Outcome type: dichotomous outcome Headache (0 to 24 hours) Outcome type: dichotomous outcome Constipation (0 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: Turkey Setting: inpatient, single‐centre Author's name: Aynur Akin Institution: Erciycs Universitcsi Tip Fakultesi Anesteziyoloji ve Reanimasyon Anabilim Dah, Kayseri Email: aaynur@erciyes.edu.tr Address: Alpaslan Mah. Kandil Sok. Bezciler Sitesi 3. Blok No:6 K:6 D:11.38030‐Melikgazi‐Kayseri Duration of study: NA Language: Turkish (translated by Emine Yesil) Study's primary outcome: NA Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Judgement comment: no information on sequence generation provided ("randomized")
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 provided ("double‐blinded manner")
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement comment: insufficient information on blinding provided ("double‐blinded manner")
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, perioperative opioids): no; (history of PONV/motion sickness, non‐smoker): unclear