Steinbrook 1998.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Ondansetron + droperidol Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 66 Age (mean ± SD, median (IQR), median (range)): 44 ± 13 Weight (mean ± SD, median (IQR), median (range)): 74 ± 17 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 81.8 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: balanced anaesthesia (desflurane, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 67 Use of perioperative opioids (if yes, which?): 225 µg fentanyl intraoperative, 55 patients received opioids in PACU Type of surgery: laparoscopic cholecystectomy Droperidol + metoclopramide Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 66 Age (mean ± SD, median (IQR), median (range)): 44 ± 14 Weight (mean ± SD, median (IQR), median (range)): 77 ± 15 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 81.8 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: balanced anaesthesia (desflurane, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 68 Use of perioperative opioids (if yes, which?): 244 µg fentanyl intraoperative, 54 patients received opioids in PACU Type of surgery: laparoscopic cholecystectomy Perphenazine Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 68 Age (mean +/‐ SD, median (IQR), median [range]): 46 +/‐ 13 Weight (mean +/‐ SD, median (IQR), median [range]): 74 +/‐ 16 BMI (mean +/‐ SD, median (IQR), median [range]): NA ASA I/II/III/IV (n): NA Gender (female in %): 77.9 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: balanced anaesthesia (desflurane, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 68 Use of perioperative opioids (if yes, which?): 230 µg fentanyl intraoperative, 51 patients received opioids in PACU Type of surgery: laparoscopic cholecystectomy Included criteria: scheduled for laparoscopic cholecystectomy 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
Interventions	Intervention characteristics Ondansetron + droperidol Dose: ondansetron 4 mg, droperidol 0.625 mg Time point of administration: immediately after tracheal intubation Route of administration: IV Rescue antiemetics (if yes, which?): NA Droperidol + metoclopramide Dose: droperidol 0.625 mg, metoclopramide 10 mg Time point of administration: immediately after tracheal intubation Route of administration: IV Rescue antiemetics (if yes, which?): NA Perphenazine Dose: perphenazine 5 mg, placebo 50 ml saline Time point of administration: immediately after tracheal intubation Route of administration: IV Rescue antiemetics (if yes, which?): NA
Outcomes	Vomiting (0 to 2 hours) Outcome type: dichotomous outcome Vomiting (2 to 24 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: USA Setting: inpatient, single‐centre Author's name: Richard A. Steinbrook Institution: Brigham and Women's Hospital, Harvard Medical School, USA Email: NA Address: Department of Anesthesia, Brigham andWomen’s Hospital, 75 Francis St., Boston, MA 02115, USA Duration of study: NA Language: English Study's primary outcome: PONV Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "assign patient treatment blocks of six from a published table of random numbers; 6 patients were stratified by gender‐adjusted percent ideal body weight"
Allocation concealment (selection bias)	Unclear risk	Quote: "antiemetic drug preparation and randomization were performed by an unblinded research pharmacist, using a computer program to assign patient treatment blocks of six..." Judgement comment: insufficient information on allocation concealment (unclear whether pharmacist could foresee allocation of the next patient)
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "physicians, nurses, and patients were blinded to the identity of the antiemetics"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement comment: no statement on blinding of outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "twelve patients required conversion to open cholecystectomy and therefore were eliminated from the study; thus, 200 patients completed the protocol and are included in the analysis"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Quote: "the groups were similar with respect to gender, age, weight, duration of surgery, intraoperative fentanyl dose, and numbers receiving intraoperative atropine or ephedrine (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