Savant 2016.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, combination prophylaxis
Participants	Baseline characteristics 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)): 38.0 ± 14.9 Weight (mean ± SD, median (IQR), median (range)): 59.2 ± 13.1 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 33 Non‐smoker (%): NA History of PONV/motion sickness (%): 0 Type of general anaesthesia: inhalational anaesthesia (halothane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 150.4 Use of perioperative opioids (if yes, which?): pentazocine (0.5 mg/kg) as premedication Type of surgery: oral and maxillofacial surgery Granisetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 30 Received treatment (n): 30 Analysed (n): 30 Age (mean ± SD, median (IQR), median (range)): 31.8 ± 11.1 Weight (mean ± SD, median (IQR), median (range)): 56.0 ± 11.8 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 23 Non‐smoker (%): NA History of PONV/motion sickness (%): 0 Type of general anaesthesia: inhalational anaesthesia (halothane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 166.4 Use of perioperative opioids (if yes, which?): pentazocine (0.5 mg/kg) as premedication Type of surgery: oral and maxillofacial surgery Included criteria: 18 to 70 years of age, weighing more than 40 kg, ASA I or II, scheduled for oral and maxillofacial surgery under general anaesthesia Excluded criteria: unable or unwilling to give informed consent, documented hypersensitivity to any of the study drugs, history of motion sickness or previous PONV, had taken antiemetic drugs within 24 hours before surgery, history of neurological or renal disease, medically compromised and not considered fit for surgery under general anaesthesia, history of adverse reactions to study drugs 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 + dexamethasone Dose: ondansetron 4 mg, dexamethasone 8 mg Time point of administration: ondansetron before induction, dexamethasone during surgery Route of administration: IV Rescue antiemetics (if yes, which?): 3.3% (metoclopramide 10 mg) Granisetron + dexamethasone Dose: granisetron 2 mg, dexamethasone 8 mg Time point of administration: granisetron before induction, dexamethasone during surgery Route of administration: IV Rescue antiemetics (if yes, which?): 0% (metoclopramide 10 mg)
Outcomes	Vomiting (0 to 2 hours) Outcome type: dichotomous outcome Nausea (0 to 24 hours) Outcome type: dichotomous outcome Complete response (no PONV) in 24 hours Outcome type: dichotomous outcome Headache (0 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: India Setting: inpatient, single‐centre Author's name: Rakshit Vijay Sinai Khandeparke Institution: Oral and Maxillofacial Surgery, Richardsons Dental and Craniofacial Hospital, Nagercoil, India Email: rockdotcom1386@gmail.com Address: Oral and Maxillofacial Surgery, Richardsons Dental and Craniofacial Hospital, #71 Trivandrum Highway, Parvathipuram, Nagercoil, Tamil Nadu 629003, India, TEL: +91‐7868096436 Language: English Duration of study: October 2011 to October 2012 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 to the two study drug groups (A and B) and in a double blind manner" 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: insufficient information on blinding
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement comment: no statement on whether outcome assessors were blinded
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): no; (non‐smoker, perioperative opioids): unclear