Grond 1995.

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): 40 Received treatment (n): 40 Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 36 ± 11 Weight (mean ± SD, median (IQR), median (range)): 65 ± 9 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 22.5/27.5 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 43 Use of perioperative opioids (if yes, which?): 0.13 mg fentanyl, 17 patients with tramadol Type of surgery: dilation and curettage, diagnostic laparoscopy Droperidol Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): 40 Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 33 ± 12 Weight (mean ± SD, median (IQR), median (range)): 68 ± 12 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 35/22.5 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 45 Use of perioperative opioids (if yes, which?): 0.13 mg fentanyl, 14 patients with tramadol Type of surgery: dilation and curettage, diagnostic laparoscopy Included criteria: ASA I and II, 18 to 65 years of age, presenting for elective diagnostic procedures of the uterus or adnexa Excluded criteria: pregnancy, drug dependence, psychiatric illness, intolerance to ondansetron or droperidol, pre‐existing nausea, intake of antiemetics 24 hours before the study, as well as respiratory, cardiovascular, hepatic, renal, or metabolic disorders Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV/motion sickness, perioperative opioids): no; (non‐smoker): unclear
Interventions	Intervention characteristics Ondansetron Dose: 8 mg Time point of administration: 5 minutes before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV; in case of failure, dimenhydrinate 150 mg IV Droperidol Dose: 2.5 mg Time point of administration: 5 minutes before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV; in case of failure, dimenhydrinate 150 mg IV
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome Nausea (0 to 24 hours) Outcome type: dichotomous outcome Complete response (no PONV) in 24 hours Outcome type: dichotomous outcome Sedation/drowsiness (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: Germany Setting: inpatient, single‐centre Author's name: Stefan Grond Institution: Department of Anesthesiology and Operative Intensive Care, University of Cologne, Cologne, Germany Email: NA Address: Klinik für Anaesthesiologie und Operative Intensivmedizin, Universität zu Köln, D‐50924 Köln, Germany Language: English Duration of study: NA Trial registry number: NA Study's primary outcome: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "were prospectively randomized to receive either ondansetron or droperidol in a double‐blind..." Judgement comment: no further information on randomization method provided
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "the syringes containing the study medication were prepared by a nurse otherwise not participating in the study" Judgement comment: no further information on blinding of personnel and identical appearance of syringes provided
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "all patients were observed by the same recovery room nurse, who did not otherwise participate in the study. During the following 22 h, the patients were monitored on the general ward by nurses who were familiar with the study" Judgement comment: insufficient information on blinding of outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "forty patients received ondansetron and 40 received droperidol. All of them completed the study"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Quote: "there were no significant differences between the groups with respect to patient characteristics, type of surgery, duration of anesthesia, and doses of anesthetics (Table 1)" Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV/motion sickness, perioperative opioids): no; (non‐smoker): unclear