Alam 2016.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 57 Age (mean ± SD, median (IQR), median (range)): 42.7 ± 1.24 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 %): 56.14 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: inhalational anaesthesia Duration of anaesthesia or surgery (in min; as mean or median): NA Use of perioperative opioids (if yes, which?): NA Type of surgery: laparoscopic cholecystectomy Metoclopramide Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 57 Age (mean ± SD, median (IQR), median (range)): 44.1 ± 1.05 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 %): 52.63 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: inhalational anaesthesia Duration of anaesthesia or surgery (in min; as mean or median): NA Use of perioperative opioids (if yes, which?): NA Type of surgery: laparoscopic cholecystectomy Included criteria: chronic cholecystitis secondary to gallstones, advised laparoscopic cholecystectomy Excluded criteria: head injuries, history of motion sickness, preexisting medical illness that can precipitate vomiting Pretreatment: baseline characteristics (age): no; (weight, BMI, ASA): unclear. Potential effect modifiers (gender, history of motion sickness): no; (history of PONV, duration of anaesthesia, non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Dexamethasone Dose: 8 mg Time point of administration: at time of induction Route of administration: IV Rescue antiemetics (if yes, which?): NA Metoclopramide Dose: 10 mg Time point of administration: at time of induction Route of administration: IV Rescue antiemetics (if yes, which?): NA
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: Saudi Arabia Setting: inpatient, single‐centre Author's name: Umar Farooq Dar Institution: Community Family Medicine, Aljouf University College of Medicine, Kingdom of Saudi Arabia Email: umardar84@gmail.com Address: NA 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: "randomized" 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	Judgement comment: baseline characteristics (age): no; (weight, BMI, ASA): unclear. Potential effect modifiers (gender, history of motion sickness): no; (history of PONV, duration of anaesthesia, non‐smoker, perioperative opioids): unclear