Dabbous 2010.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, combination prophylaxis
Participants	Baseline characteristics Granisetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 42 Age (mean ± SD, median (IQR), median (range)): 46.5 ± 11.7 Weight (mean ± SD, median (IQR), median (range)): 75.8 ± 16.1 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 47.62 Non‐smoker (%): 52.38 History of PONV/motion sickness (%): 11.90/2.38 Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 61 Use of perioperative opioids (if yes, which?): intraoperative fentanyl Type of surgery: laparoscopic cholecystectomy or herniorrhaphy Ondansetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 42 Age (mean ± SD, median (IQR), median (range)): 47.4 ± 14.2 Weight (mean ± SD, median (IQR), median (range)): 77.5 ± 14.1 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 52.38 Non‐smoker (%): 57.14 History of PONV/motion sickness (%): 9.52/4.76 Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 62 Use of perioperative opioids (if yes, which?): intraoperative fentanyl Type of surgery: laparoscopic cholecystectomy or herniorrhaphy Included criteria: ASA I or II, scheduled for laparoscopic cholecystectomy or herniorrhaphy Excluded criteria: known allergies or hypersensitivity to study drugs, history of chronic nausea and vomiting or experienced nausea and vomiting in the past 24 hours before anaesthesia, had received any antiemetics or any drug with antiemetic properties during the 24 hours before anaesthesia, BMI ≥ 35 kg/m², over 70 years of age, pregnant or breastfeeding, had a condition requiring long‐term opioid use Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of PONV/motion sickness): no; (perioperative opioids): unclear
Interventions	Intervention characteristics Granisetron + dexamethasone Dose: granisetron 1 mg, dexamethasone 8 mg Time point of administration: immediately after induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV Ondansetron + dexamethasone Dose: ondansetron 4 mg, dexamethasone 8 mg Time point of administration: immediately after induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV
Outcomes	Vomiting (6 to 24 hours) Outcome type: dichotomous outcome Headache (PACU) Outcome type: dichotomous outcome Sedation/drowsiness (PACU) 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: Lebanon Setting: inpatient, single‐centre Author's name: Alia Dabbous Institution: Department of Anesthesiology, American University of Beirut Medical Center, Beirut, Lebanon Email: ad00@aub.edu.lb Address: Department of Anesthesiology, American University of Beirut. P.O. Box 11‐0236, Beirut 1107‐2020, Lebanon 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)	Low risk	Quote: "using a computer generated randomization method"
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "were presented to blinded investigators as identical 2 ml filled syringes" Quote: "the study medications were prepared by a resident, who was not involved in any other part of the study, and were presented to blinded investigators..."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "adverse events were evaluated and recorded by a resident who was blinded to the study drugs used"
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "of the 100 patients initially signing the informed consent, 84 patients (42 in group I, 42 in group II) completed the study" Judgement comment: missing data > 15%. No reasons mentioned for loss of participants
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 was no statistically significant difference between the two groups in regards to gender, history of PONV and history of motion sickness, age, weight, type of surgery (laparoscopic cholecystectomy or laparoscopic herniorraphy), duration of surgery, history of prolonged gastric emptying, and smoking history (Table 1)" Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of PONV/motion sickness): no; (perioperative opioids): unclear