Rajeeva 1999.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Ondansetron (group I) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 26 Received treatment (n): 26 Analysed (n): 26 Age (mean ± SD, median (IQR), median (range)): 28.85 ± 5.29 Weight (mean ± SD, median (IQR), median (range)): 48.88 ± 6.38 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 26/0/0/0 Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 0 Type of general anaesthesia: inhalational anaesthesia (N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 28.54 Use of perioperative opioids (if yes, which?): 1 mg/kg meperidine intraoperative Type of surgery: gynaecological diagnostic laparoscopy Ondansetron + dexamethasone (group II) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 25 Received treatment (n): 25 Analysed (n): 25 Age (mean ± SD, median (IQR), median (range)): 28.72 ± 4.46 Weight (mean ± SD, median (IQR), median (range)): 50.84 ± 6.92 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 25/0/0/0 Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): 0 Type of general anaesthesia: inhalational anaesthesia (N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 29.00 Use of perioperative opioids (if yes, which?): 1 mg/kg meperidine intraoperative Type of surgery: gynaecological diagnostic laparoscopy Included criteria: ASA I, female, 20 to 40 years of age, undergoing elective diagnostic laparoscopy under general anaesthesia Excluded criteria: obese (BW 20% more than expected for their age), pregnant, history of motion sickness or PONV, had received antiemetics within 24 hours of surgery, needing long‐term steroid therapy, diabetes mellitus, intestinal obstruction or hiatus hernia Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV/motion sickness): no; (non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Ondansetron (group I) Dose: 4 mg Time point of administration: soon after tracheal intubation Route of administration: IV Rescue antiemetics (if yes, which?): 0.15 mg/kg metoclopramide; the need for rescue antiemetics did not differ between the 2 groups Ondansetron + dexamethasone (group II) Dose: ondansetron 4 mg + dexamethasone 8 mg Time point of administration: soon after tracheal intubation Route of administration: IV Rescue antiemetics (if yes, which?): 0.15 mg/kg metoclopramide; the need for rescue antiemetics did not differ between the 2 groups
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome Vomiting (0 to 2 hours) Outcome type: dichotomous outcome Vomiting (2 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: India Setting: NA, single‐centre Author's name: Neerja Bhardwaj Institution: Departments of Anaesthesia and Obstetrics and Gynaecology, Post Graduate Institute of Medical Education and Research, Chandigarh Email: NA Address: Flat No. 124‐C, Sector 24‐A, Chandigarh, India 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: "randomly divided by random number chart into two groups"
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	Quote: "the two groups were comparable regarding age, weight, last menstrual period (LMI'), duration of procedure, and duration of insufflation" Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of PONV/motion sickness): no; (non‐smoker, perioperative opioids): unclear