Weren 2008.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis
Participants	Baseline characteristics Dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 38 Received treatment (n): NA Analysed (n): 38 Age (mean ± SD, median (IQR), median (range)): 45.03 ± 16.07 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 28.05 ± 10.50 ASA I/II/III/IV (n): NA Gender (female in %): 100 Non‐smoker (%): 86.85 History of PONV/motion sickness (%): 10.53/NA Type of general anaesthesia: inhalational anaesthesia (desflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 112.5 Use of perioperative opioids (if yes, which?): 26.51 µg sufentanil, 10 mg piritramide Type of surgery: gynaecological, laparoscopic, abdominal Methylprednisolone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): NA Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 45.35 ± 15.23 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 25.20 ± 20 ASA I/II/III/IV (n): NA Gender (female in %): 100 Non‐smoker (%): 67.5 History of PONV/motion sickness (%): 7.50/NA Type of general anaesthesia: inhalational anaesthesia (desflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 127.5 Use of perioperative opioids (if yes, which?): 27.94 µg sufentanil, 10 mg piritramide Type of surgery: gynaecological, laparoscopic, abdominal Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): 40 Analysed (n): 40 Age (mean ± SD, median (IQR), median (range)): 47.28 ± 16.58 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 25.80 ± 7.45 ASA I/II/III/IV (n): NA Gender (female in %): 100 Non‐smoker (%): 87.5 History of PONV/motion sickness (%): 10.00/NA Type of general anaesthesia: inhalational anaesthesia (desflurane, N₂O) Duration of anaesthesia or surgery (in min; as mean or median): 105.0 Use of perioperative opioids (if yes, which?): 23.94 µg sufentanil, 10 mg piritramide Type of surgery: gynaecological, laparoscopic, abdominal Included criteria: female adult, elective abdominal or gynaecological surgery, informed consent Excluded criteria: pregnancy, lactation, intake of antiemetic drugs within 24 hours preceding surgery and emergency procedure Pretreatment: baseline characteristics (age, BMI): no; (ASA): unclear. Potential effect modifiers (gender, history of PONV): no; (history of motion sickness): unclear; (perioperative opioids, non‐smoker, duration of anaesthesia): yes
Interventions	Intervention characteristics Dexamethasone Dose: 8 mg Time point of administration: at induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): alizapride 50 mg or ondansetron 4 mg Methylprednisolone Dose: 40 mg Time point of administration: at induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): alizapride 50 mg or ondansetron 4 mg Placebo Dose: normal saline Time point of administration: at induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): alizapride 50 mg or ondansetron 4 mg
Outcomes	Vomiting (0 to 2 hours) Outcome type: dichotomous outcome Vomiting (2 to 24 hours) Outcome type: dichotomous outcome PONV (0 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: Belgium Setting: inpatient, single‐centre Author's name: Matijn Weren Institution: Kliniek St. Jan, Brussels, Kruidtuinlaan 32, 1000 Brussel Email: matijnweren@yahoo.co.uk Address: UZ Gasthuisberg, Department of Anesthesia, Herestraat 49, 3000 Leuven Language: English Duration of study: NA Trial registry number: NA Study's primary outcome: primary endpoint is to compare dexamethasone and methylprednisolone to placebo for prevention of PONV
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Judgement comment: "patients were randomized in three groups by a computer generated list"
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Judgement comment: "prophylactic anti‐emetic drugs were given according to the randomization in a double‐blind matter. all patients were given a 10 ml intravenous solution at the induction of anaesthesia". Insufficient information on blinding
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	High risk	Judgement comment: quote: "there were no significant differences between our 3 groups with regard to age, type of surgery, body mass index (BMI), history of PONV, smoking status, use of N₂O or use of clonidine. Duration of anaesthesia was significantly longer in the methylprednisolone group in comparison with placebo. Significantly more sufentanil was used in the methylprednisolon group in comparison with placebo.Neither the use of sufentanil nor the duration of anaesthesia was significantly different between the two steroid groups" Baseline characteristics (age, BMI): no; (ASA): unclear. Potential effect modifiers (gender, history of PONV): no; (history of motion sickness): unclear; (perioperative opioids, non‐smoker, duration of anaesthesia): yes