Fabling 2000.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Ondansetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 47 ± 11 Weight (mean ± SD, median (IQR), median (range)): 76 ± 18 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/NA/0 Gender (female in %): 55 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 328 Use of perioperative opioids (if yes, which?): 1250 µg intraoperative fentanyl, codeine as rescue analgesic Type of surgery: supratentorial craniotomy Droperidol + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 52 ± 12 Weight (mean ± SD, median (IQR), median (range)): 82 ± 22 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/NA/0 Gender (female in %): 60 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 281 Use of perioperative opioids (if yes, which?): 1189 µg intraoperative fentanyl, codeine as rescue analgesic Type of surgery: supratentorial craniotomy Dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 45 ± 12 Weight (mean ± SD, median (IQR), median (range)): 85 ± 19 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/NA/0 Gender (female in %): 45 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 312 Use of perioperative opioids (if yes, which?): 1169 µg intraoperative fentanyl, codeine as rescue analgesic Type of surgery: supratentorial craniotomy Included criteria: 18 to 75 years of age, scheduled for elective supratentorial craniotomy for mass lesion Excluded criteria: ASA IV or V, antiemetic use preoperatively or intraoperatively, allergy to ondansetron or droperidol, pregnancy, breastfeeding, morbid obesity, mental retardation, psychiatric illness Pretreatment: baseline characteristics (age, weight): no; (ASA): unclear. Potential effect modifiers (gender, duration of anaesthesia, perioperative opioids): no; (history of PONV/motion sickness, non‐smoker): unclear
Interventions	Intervention characteristics Ondansetron + dexamethasone Dose: ondansetron 4 mg, "large dose" dexamethasone Time point of administration: on surgical commencement of skin closure, dexamethasone intraoperatively Route of administration: IV Rescue antiemetics (if yes, which?): 40% (trimethobenzamide 200 mg, ondansetron 4 mg) Droperidol + dexamethasone Dose: droperidol 0.625 mg, "large dose" dexamethasone Time point of administration: on surgical commencement of skin closure, dexamethasone intraoperatively Route of administration: IV Rescue antiemetics (if yes, which?): 40% (trimethobenzamide 200 mg, ondansetron 4 mg) Dexamethasone Dose: "large dose" dexamethasone Time point of administration: intraoperatively Route of administration: IV Rescue antiemetics (if yes, which?): 50% (trimethobenzamide 200 mg, ondansetron 4 mg)
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome Nausea (0 to 24 hours) or PONV 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: USA Setting: inpatient, single‐centre Author's name: Cecil O. Borel Institution: Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA Email: borel001@mc.duke.edu Address: Department of Anesthesiology, DUMC Box 3094, Duke University, Durham, NC 27710, USA Language: English Duration of study: NA Trial registry number: NA Study's primary outcome: incidence of PONV
Notes	Dexamethasone given perioperatively; dose unknown but stated "was not different between groups"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly assigned to one of three groups" Judgement comment: 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	Quote: "study drugs were prepared by a pharmacist and administered by the anesthesia staff not involved in data collection. Study..." Judgement comment: no information on blinding of anaesthesiologists
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement comment: insufficient information on blinding ("double‐blind")
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: "all groups were demographically similar, and there was no difference in duration of anesthesia or total fentanyl dose administered (Table 1)" Judgement comment: baseline characteristics (age, weight): no; (ASA): unclear. Potential effect modifiers (gender, duration of anaesthesia, perioperative opioids): no; (history of PONV/motion sickness, non‐smoker): unclear