Jo 2012.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Ramosetron (group R) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): 40 Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 48 ± 13 Weight (mean ± SD, median (IQR), median (range)): 58 ± 9 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 100 Non‐smoker (%): 0 History of PONV/motion sickness (%): 2.5/12.5 Type of general anaesthesia: balanced anaesthesia (sevoflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 67 Use of perioperative opioids (if yes, which?): remifentanil intraoperative, 1 µg/kg fentanyl postoperative Type of surgery: laparoscopic cholecystectomy Dexamethasone (group D) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): 40 Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 44 ± 12 Weight (mean ± SD, median (IQR), median (range)): 60 ± 9 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 100 Non‐smoker (%): 0 History of PONV/motion sickness (%): 0/10 Type of general anaesthesia: balanced anaesthesia (sevoflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 69 Use of perioperative opioids (if yes, which?): remifentanil intraoperative, 1 µg/kg fentanyl postoperative Type of surgery: laparoscopic cholecystectomy Ramosetron + dexamethasone (group RD) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): 40 Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 44 ± 10 Weight (mean ± SD, median (IQR), median (range)): 58 ± 8 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 100 Non‐smoker (%): 0 History of PONV/motion sickness (%): 0/5 Type of general anaesthesia: balanced anaesthesia (sevoflurane, remifentanil) Duration of anaesthesia or surgery (in min; as mean or median): 71 Use of perioperative opioids (if yes, which?): remifentanil intraoperative, 1 µg/kg fentanyl postoperative Type of surgery: laparoscopic cholecystectomy Included criteria: female, scheduled for elective laparoscopic cholecystectomy under general anaesthesia Excluded criteria: ASA III or IV; smoking status; antiemetic medication within 24 hours before surgery; administration of steroids within 24 hours before surgery or during the 24 hours after surgery; gastrointestinal, renal, or hepatic disease; insulin‐dependent diabetes mellitus; obesity (body mass index > 35 kg/m²); conversion to open cholecystectomy 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 Ramosetron (group R) Dose: 0.3 mg Time point of administration: placebo before induction of anaesthesia, ramosetron approximately 15 minutes before end of surgery Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV Dexamethasone (group D) Dose: 8 mg Time point of administration: dexamethasone before induction of anaesthesia, placebo approximately 15 minutes before end of surgery Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV Ramosetron + dexamethasone (group RD) Dose: ramosetron 0.3 mg, dexamethasone 8 mg Time point of administration: dexamethasone before induction of anaesthesia, ramosetron approximately 15 minutes before end of surgery Route of administration: IV Rescue antiemetics (if yes, which?): metoclopramide 10 mg IV
Outcomes	Vomiting (0 to 6 hours) Outcome type: dichotomous outcome Vomiting (6 to 12 hours) Outcome type: dichotomous outcome PONV (0 to 24 hours) Outcome type: dichotomous outcome Headache (0 to 24 hours) 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: Republic of Korea Setting: inpatient, single‐centre Author's name: Yong Seon Choi Institution: Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea Email: yschoi@yuhs.ac Address: Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 50 Yonsei‐ro, Seodaemun‐gu, Seoul 120‐752, Republic of Korea Duration of study: NA Language: English Study's primary outcome: complete response during 24 hours 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 list"
Allocation concealment (selection bias)	Unclear risk	Judgement comment: not stated: "sequentially numbered, opaque, and sealed envelopes" (SNOSE)
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "the envelopes were opened before anesthetic induction by a physician not involved in the study. The physician then prepared the appropriate study medication"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement comment: no statement
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "total of 146 patients were assessed for eligibility; 120 of these patients were enrolled in the study and completed surgical procedures (Fig. 1)"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Quote: "patients’ characteristics and operative data were all similar among the three groups (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