Shora 2007.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Ondansetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 30 Received treatment (n): 30 Analysed (n): 30 Age (mean ± SD, median (IQR), median (range)): 33.27 ± 8.53 Weight (mean ± SD, median (IQR), median (range)): 52.90 ± 7.27 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: inhalational anaesthesia (N₂O, halothane) Duration of anaesthesia or surgery (in min; as mean or median): 65.27 Use of perioperative opioids (if yes, which?): morphine for induction Type of surgery: laparoscopic cholecystectomy Ondansetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 30 Received treatment (n): 30 Analysed (n): 30 Age (mean ± SD, median (IQR), median (range)): 32.47 ± 10.18 Weight (mean ± SD, median (IQR), median (range)): 52.70 ± 7.47 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: inhalational anaesthesia (N₂O, halothane) Duration of anaesthesia or surgery (in min; as mean or median): 66.67 Use of perioperative opioids (if yes, which?): morphine for induction Type of surgery: laparoscopic cholecystectomy Included criteria: female, 18 to 55 years of age, ASA I or II, undergoing laparoscopic cholecystectomy under general anaesthesia Excluded criteria: history of motion sickness, migraine, PONV during previous surgery, pregnant or lactating 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: 4 mg Time point of administration: 1 minute before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): ondansetron 0.1 mg/kg Ondansetron + dexamethasone Dose: ondansetron 4 mg, dexamethasone 4 mg Time point of administration: 1 minute before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): ondansetron 0.1 mg/kg
Outcomes	Vomiting (0 to 6 hours) Outcome type: dichotomous outcome Vomiting (12 to 18 hours) Outcome type: dichotomous outcome PONV (0 to 24 hours) Outcome type: dichotomous outcome Complete response (no PONV) in 24 hours Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: India Setting: inpatient, single‐centre Author's name: Asaf Nazir Shora Institution: Sher‐i‐Kashmir Institute of Medical Sciences Email: NA Address: Soura, Bemina, Srinagar, Jammu and Kashmir 190011 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: "patients were randomly allocated into two groups of 30 patients each" 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	Quote: "patients included in the study. In the preoperative holding area, patients were randomly allocated into two groups of 30 patients each and received study medications prepared by a single person in identical 5 ml syringe and all study medications were diluted up to 4 ml in 0.9 % saline in order to ensure blinding" Judgement comment: it is unclear whether the person preparing the syringes was further involved in the study
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "after surgery patients were observed for a period of 24 hours by the same anaesthetist" Judgement comment: insufficient information on blinding of outcome assessors
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, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV/motion sickness, perioperative opioids): no; (non‐smoker): unclear