Ahsan 2014.

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): 50 Received treatment (n): NA Analysed (n): 50 Age (mean ± SD, median (IQR), median (range)): 41.32 ± 12.9 Weight (mean ± SD, median (IQR), median (range)): 60 ± 9.25 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 29/21/0/0 Gender (female in %): 86 Non‐smoker (%): NA History of PONV/motion sickness (%): 0 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): NA Use of perioperative opioids (if yes, which?): nalbuphine 10mg at induction Type of surgery: laparoscopic cholecystectomy Ondansetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 50 Received treatment (n): NA Analysed (n): 50 Age (mean ± SD, median (IQR), median (range)): 44.48 ± 14.5 Weight (mean ± SD, median (IQR), median (range)): 60 ± 8.5 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 24/26/0/0 Gender (female in %): 82 Non‐smoker (%): NA History of PONV/motion sickness (%): 0 Type of general anaesthesia: inhalational anaesthesia (isoflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): NA Use of perioperative opioids (if yes, which?): nalbuphine 10 mg at induction Type of surgery: laparoscopic cholecystectomy Included criteria: ASA I and II, 20 to 70 years of age, laparoscopic cholecystectomy Excluded criteria: ASA III and IV; preoperative emesis or pregnant or taking sedatives, anxiolytics, antihistamines, and antiemetics or with known history of drug allergy, hypersensitivity to antiemetics, or with ear disease and vertigo or menstruation at the time of surgery (because menstruation can provoke nausea and vomiting, which could affect the outcome of the study) or history of postoperative emesis; history of motion sickness Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, history of PONV/motion sickness): no; (perioperative opioids, duration of anaesthesia, 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?): 28% required metoclopramide 10 mg (nausea lasted longer than 15 minutes or vomiting has occurred) Ondansetron + dexamethasone Dose: ondansetron 4 mg, dexamethasone 8 mg Time point of administration: 1 minute before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): 12% required metoclopramide 10 mg (nausea lasted longer than 15 minutes or vomiting has occurred)
Outcomes	Vomiting (0 to 6 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: Pakistan Setting: single centre, no other information provided Author's name: Ahsan Khalid Institution: Department of Anesthesiology, Aga Khan University Email: khalid.ahsan@aku.edu Address: Liaquat National Hospital, Karachi Language: English Duration of study: 23 April 2009 to 22 August 2009 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: "they were randomly divided into Group A and Group B with sealed envelope technique of 50 patients in each group"
Allocation concealment (selection bias)	Unclear risk	Quote: "with sealed envelope technique of 50 patients in each group" Judgement comment: not mentioned SNOSE
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, weight, ASA): no. Potential effect modifiers (gender, history of PONV/motion sickness): no; (perioperative opioids, duration of anaesthesia, non‐smoker): unclear