Watts 1996.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis
Participants	Baseline characteristics Ondansetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 59 Age (mean ± SD, median (IQR), median (range)): 30.5 ± 5.68 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 27/25 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 20 to 30 Use of perioperative opioids (if yes, which?): 1.5 µg/kg fentanyl at induction, 9.4 mg morphine postoperative Type of surgery: laparoscopic procedure Metoclopramide Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 55 Age (mean ± SD, median (IQR), median (range)): 30.9 ± 2.89 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 20/20 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 20 to 30 Use of perioperative opioids (if yes, which?): 1.5 µg/kg fentanyl at induction, 8.7 mg morphine postoperative Type of surgery: laparoscopic procedure Cyclizine Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 53 Age (mean ± SD, median (IQR), median (range)): 30.3 ± 7.06 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 23/28 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 20 to 30 Use of perioperative opioids (if yes, which?): 1.5 µg/kg fentanyl at induction, 8.4 mg morphine postoperative Type of surgery: laparoscopic procedure Included criteria: women presenting for elective laparoscopic procedure on a day‐stay basis Excluded criteria: pregnant, had taken any opiate or antiemetic in the preceding 24 hours, history of hypersensitivity to any of the trial agents, on assessment were deemed to be better served by an anaesthetic different from the standard technique (obesity, reflux, difficult airway) Pretreatment: baseline characteristics (age): no; (weight, BMI, ASA): unclear. Potential effect modifiers (gender, history of PONV/motion sickness, perioperative opioids): no; (duration of anaesthesia, non‐smoker): unclear
Interventions	Intervention characteristics Ondansetron Dose: 4 mg Time point of administration: immediately following cannula insertion Route of administration: IV Rescue antiemetics (if yes, which?): prochlorperazine 12.5 mg IM Metoclopramide Dose: 10 mg Time point of administration: immediately following cannula insertion Route of administration: IV Rescue antiemetics (if yes, which?): prochlorperazine 12.5 mg IM Cyclizine Dose: 50 mg Time point of administration: immediately following cannula insertion Route of administration: IV Rescue antiemetics (if yes, which?): prochlorperazine 12.5 mg IM
Outcomes	PONV (0 to 24 hours) Outcome type: dichotomous outcome Extrapyramidal symptoms (0 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: New Zealand Setting: outpatient, single‐centre Author's name: S.A. Watts Institution: Palmerston North Hospital, Palmerston North, New Zealand Email: NA Address: Department of Anaesthesia, Waikato Hospital, Hamilton, New Zealand Duration of study: NA Language: English Study's primary outcome: incidence of PONV Trial registry number: NA
Notes	Two studies (1 non‐randomized pilot study, 1 RCT)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "the second phase was a randomized, double‐blind comparison of the efficacy of the three study antiemetics" Judgement comment: no further information on sequence generation provided
Allocation concealment (selection bias)	Unclear risk	Quote: "all test agents were supplied to the administering anaesthetist in capped and coded syringes containing 2 ml of colourless liquid" Judgement comment: insufficient information on allocation concealment and time point of randomization
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "all test agents were supplied to the administering anaesthetist in capped and coded syringes containing 2 ml of colourless liquid"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "...hours postoperatively and at time of discharge from the day‐stay unit (usually four to six hours post operation), by the attending nursing staff. Scores at 24 hours were attained by phone or standard questionnaire via return mail by the investigator" Judgement comment: no information on blinding of outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "...166 making up the comparative trial population. Of the patients in the comparative trial, 54 were given metoclopramide (Group M), 59 received ondansetron (Group O) and 53 cyclizine (Group C)"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Quote: "...similar in the three groups for mean patient age, day of menstrual cycle and type of operation. Distribution of patients with a past history of motion sickness or previous PONV was comparable between groups and likewise there was no difference of significance in the distribution of operative procedures" Judgement comment: baseline characteristics (age): no; (weight, BMI, ASA): unclear. Potential effect modifiers (gender, history of PONV/motion sickness, perioperative opioids): no; (duration of anaesthesia, non‐smoker): unclear