Ganem 2002.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Placebo (group 1) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 31 ± 6 Weight (mean ± SD, median (IQR), median (range)): 59 ± 11 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 (%): 0 Type of general anaesthesia: TIVA (propofol, sufentanil), N₂O Duration of anaesthesia or surgery (in min; as mean or median): 90 Use of perioperative opioids (if yes, which?): intraoperative sufentanil, tramadol as rescue analgesic Type of surgery: gynaecological laparoscopy Dexamethasone (group 2) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 30 ± 7 Weight (mean ± SD, median (IQR), median (range)): 62 ± 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 (%): 0 Type of general anaesthesia: TIVA (propofol, sufentanil), N₂O Duration of anaesthesia or surgery (in min; as mean or median): 87 Use of perioperative opioids (if yes, which?): intraoperative sufentanil, tramadol as rescue analgesic Type of surgery: gynaecological laparoscopy Included criteria: women, 18 to 46 years of age, ASA I or II, body mass index < 30, undergoing diagnostic or surgical gynaecological laparoscopy Excluded criteria: current or previous gastric complaints, history of nausea and vomiting with previous anaesthesia, motion sickness, psychiatric disease, menstruating, alcohol or drug users Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, history of PONV/motion sickness, duration of anaesthesia): no; (non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Placebo (group 1) Dose: saline Time point of administration: immediately before anaesthetic induction Route of administration: IV Rescue antiemetics (if yes, which?): ondansetron 4 mg IV Dexamethasone (group 2) Dose: 8 mg Time point of administration: immediately before anaesthetic induction Route of administration: IV Rescue antiemetics (if yes, which?): ondansetron 4 mg IV
Outcomes	Vomiting (PACU, 0 to 1 hour) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: Brazil Setting: NA Author's name: Eliana Marisa Ganem Institution: Departamento de Anestesiologia da Faculdade de Medicina de Botucatu (FMB ‐ UNESP), Botucatu, SP Email: NA Address: Deptº de Anestesiologia da FMB ‐ UNESP, Distrito de Rubião Júnior, 18618‐970 Botucatu, SP Duration of study: NA Language: English Study's primary outcome: NA Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly distributed in two groups according to the antiemetic scheme" 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	Judgement comment: no statement
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement comment: no statement
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: "...for nausea and vomiting. Both groups were homogeneous in age, weight and height, as well as anesthesia and surgery duration (Table I)" Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, history of PONV/motion sickness, duration of anaesthesia): no; (non‐smoker, perioperative opioids): unclear