NCT00888329.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Aprepitant Assessed for eligibility (n): NA Enrolled (n): NA Randomized (n): 125 Received treatment (n): NA Analysed (n): 35/34 (efficacy/safety) Age (mean ± SD, median (IQR), median (range)): 60 (12) Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/NA/0 Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: standardized anaesthesia Duration of anaesthesia or surgery (in min; as mean or median): NA Use of perioperative opioids (if yes, which?): NA Type of surgery: hysterectomy Placebo Assessed for eligibility (n): NA Enrolled (n): NA Randomized (n): 131 Received treatment (n): NA Analysed (n): 59/37 (efficacy/safety) Age (mean ± SD, median (IQR), median (range)): 53 (12) Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/NA/0 Gender (female in %): 100 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: standardized anaesthesia Duration of anaesthesia or surgery (in min; as mean or median): NA Use of perioperative opioids (if yes, which?): NA Type of surgery: hysterectomy Included criteria: scheduled for elective hysterectomy at Mayo Clinic in Arizona; ASA I, II, or III Excluded criteria: pregnancy; concomitant bowel surgery other than appendectomy; hypersensitivity to study drug or rescue medication; preoperative score for nausea > 4 out of 10 points; severe hepatic insufficiency (Child‐Pugh score > 9); any condition that impairs the patient's ability to complete study assessments; intraoperative haemodynamic instability; ICU admission; prolonged postoperative intubation; rifampin, carbamazepine, phenytoin, or other drugs that strongly induce CYP3A4 activity; other antiemetic within 12 hours before surgery; participation in a clinical trial using an investigational product Pretreatment: baseline characteristics (age): no; (weight, ASA): unclear. Potential effect modifiers (gender): no; (history of PONV/motion sickness, non‐smoker, perioperative opioids, duration of surgery): unclear
Interventions	Intervention characteristics Aprepitant Dose: 40 mg Time point of administration: before anaesthesia induction Route of administration: PO Rescue antiemetics (if yes, which?): NA Placebo Dose: NA Time point of administration: NA Route of administration: NA Rescue antiemetics (if yes, which?): NA
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: Mayo Clinic Country: USA Setting: inpatient/outpatient, single‐centre Author's name: Javier Magrina Institution: Mayo Clinic, Phoenix, Arizona, United States, 85054, USA Email: magrina.javier@mayo.edu Address: Mayo Clinic, Phoenix, Arizona, United States, 85054, USA Duration of study: July 2007 to October 2011 Language: English Study's primary outcome: number of patients with emesis within 24 hours Trial registry number: NCT00888329
Notes	Results posted only on ClinicalTials.gov (study terminated due to slow accrual)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quote: "results might have been influenced by selection bias“ (comment in limitations and caveats)
Allocation concealment (selection bias)	High risk	Quote "results might have been influenced by selection bias“ (comment in limitations and caveats)
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote “masking: quadruple (participant, care provider, investigator, outcome assessor)” Judgement comment: no other statements
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote “masking: quadruple (participant, care provider, investigator, outcome assessor)” Judgement comment: no other statements
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote “primary outcome measure was not recorded for 84 participants in the Aprepitant group and 63 participants in the Placebo group” Judgement comment: substantial amount of missing data; no reason given
Selective reporting (reporting bias)	Unclear risk	Judgement comment: NCT00888329 (retrospective registration)
Other bias	Unclear risk	Judgement comment: baseline characteristics (age): no; (weight, ASA): unclear. Potential effect modifiers (gender): no; (history of ponv/motion sickness, non‐smoker, perioperative opioids, duration of surgery): unclear