Bianchin 2007.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline Characteristics Dexamethasone (group DESA) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 36 Age (mean ± SD, median (IQR), median (range)): 55 (24 to 80) Weight (mean ± SD, median (IQR), median (range)): 69 (51 to 104) BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 69.44 Non‐smoker (%): NA History of PONV/motion sickness (%): 0/NA Type of general anaesthesia: inhalational anaesthesia (sevoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 78 Use of perioperative opioids (if yes, which?): fentanyl for anaesthesia up to 3 µg/kg Type of surgery: laparoscopic cholecystectomy Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 37 Age (mean ± SD, median (IQR), median (range)): 56 (31 to 80) Weight (mean ± SD, median (IQR), median (range)): 71 (49 to 100) BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 59.46 Non‐smoker (%): NA History of PONV/motion sickness (%): 0/NA Type of general anaesthesia: inhalational anaesthesia (sevoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 86 Use of perioperative opioids (if yes, which?): fentanyl for anaesthesia up to 3 µg/kg Type of surgery: laparoscopic cholecystectomy Included criteria: scheduled for laparoscopic cholecystectomy Excluded criteria: ASA status III and IV, over 80 years or under 20 years of age, endoscopic retrograde cholangiopancreatography within 1 month before operation, chronic pain disorder; history of alcohol abuse, uncontrolled metabolic disease (diabetes mellitus, hypertension), previous PONV for general anaesthesia Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV): no; (history of motion sickness, non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Dexamethasone (group DESA) Dose: 8 mg Time point of administration: 2 minutes before beginning of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV Placebo Dose: normal saline Time point of administration: 2 minutes before beginning of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome Nausea (0 to 24 hours) Outcome type: dichotomous outcome Subjects with any SAE (postoperatively) Outcome type: dichotomous outcome Subjects with any AE (postoperatively) Outcome type: dichotomous outcome Postoperative wound infection (postoperatively) 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: Italy Setting: inpatient, single‐centre Author's name: A. Bianchin Institution: Anesthesia Department, ASL 8 Asolo, G. Carretta City Hospital, Montebelluna, Treviso, Italy Email: andbia@libero.it Address: Via Marco Polo 25/7, 31031 Caerano S. Marco (TV), Italy 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)	Low risk	Quote: "each patient was allocated randomly to one of the two groups using a computer‐generated random number table"
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "patient, anaesthesiologist, surgeon and nurses were all blinded with respect to the study group"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "nurses were all blinded with respect to the study group" Judgement comment: no information on outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "eighty patients were enrolled. Seven were excluded: 4 laparotomic conversions, 2 for anaesthesiological reasons (droperidol, fentanyl over 3 µg/kg), 1 laparoscopic [cholecystectomy and hernioplasty]. Seventy‐three patients have 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	Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV): no; (history of motion sickness, non‐smoker, perioperative opioids): unclear