Scuderi 1999.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Ondansetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 285 Received treatment (n): NA Analysed (n): 285 Age (mean ± SD, median (IQR), median (range)): 37.5 ± 11 Weight (mean ± SD, median (IQR), median (range)): 175 ± 46 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 63.5 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: balanced anaesthesia (99.3% fentanyl, 93% N₂O, 45.7% isoflurane, 54% sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 62 Use of perioperative opioids (if yes, which?): 283 patients received intraoperative fentanyl, 1 patient received morphine Type of surgery: "outpatient surgery" Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 290 Received treatment (n): NA Analysed (n): 290 Age (mean ± SD, median (IQR), median (range)): 39 ± 12 Weight (mean ± SD, median (IQR), median (range)): 174 ± 48 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 63.1 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: balanced anaesthesia (99.7% fentanyl, 96.2% N₂O, 46.2% isoflurane, 53.8% sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 67 Use of perioperative opioids (if yes, which?): 289 patients received intraoperative fentanyl, no patients received morphine Type of surgery: "outpatient surgery" Included criteria: men and women, 18 to 65 years of age, ASA I to III, undergoing outpatient surgery or for short stay (23 hours or less) Excluded criteria: NA 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 (however ‐> stratification to eight subgroups on the presence of PONV risk factors)
Interventions	Intervention characteristics Ondansetron Dose: 4 mg Time point of administration: at induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): randomized to 1 mg ondansetron or saline Placebo Dose: saline Time point of administration: at induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): randomized to 1 mg ondansetron or saline
Outcomes	Vomiting (0 to 2 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: financial support was received from the Department of Anesthesiology, Wake Forest University School of Medicine Country: USA Setting: outpatient, single‐centre Author's name: Phillip E. Scuderi Institution: Wake Forest University School of Medicine, North Carolina, USA Email: pscuderi@wfubmc.edu Address: Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston‐Salem, North Carolina 27157‐1009, USA Duration of study: NA Language: English Study's primary outcome: patient satisfaction with management of PONV, time to discharge from PACU Trial registry number: NA
Notes	There is a second randomization for participants who require treatment of PONV (ondansetron vs placebo)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Judgement comment: quote: "...by random number table"
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	Unclear risk	Judgement comment: insufficient information on blinding ("double‐blinded")
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): no; (ASA): unclear. Potential effect modifiers (gender, duration of anaesthesia, perioperative opioids): no; (history of PONV/motion sickness, non‐smoker): unclear (however ‐> stratification to eight subgroups on the presence of PONV risk factors)