Piper 2003.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Dolasetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 75 Received treatment (n): NA Analysed (n): 75 Age (mean ± SD, median (IQR), median (range)): 52 ± 12 Weight (mean ± SD, median (IQR), median (range)): 67 ± 12 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 29/37/9/0 Gender (female in %): 100 Non‐smoker (%): 65.33 History of PONV/motion sickness (%): 24/20 Type of general anaesthesia: balanced anaesthesia (desflurane, N₂O, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 111 Use of perioperative opioids (if yes, which?): fentanyl intraoperative, 3.75 mg piritramide postoperative Type of surgery: hysterectomy, breast surgery Dolasetron + dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 75 Received treatment (n): NA Analysed (n): 75 Age (mean ± SD, median (IQR), median (range)): 54 ± 12 Weight (mean ± SD, median (IQR), median (range)): 69 ± 13 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 22/46/7/0 Gender (female in %): 100 Non‐smoker (%): 69.33 History of PONV/motion sickness (%): 21.33/16 Type of general anaesthesia: balanced anaesthesia (desflurane, N₂O, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 117 Use of perioperative opioids (if yes, which?): fentanyl intraoperative, 3.75 mg piritramide postoperative Type of surgery: hysterectomy, breast surgery Included criteria: women, ASA I to III, undergoing elective hysterectomy or breast surgery Excluded criteria: known intolerance or allergy to any of the drugs used in the study, positive gastritis or ulcer history, pregnancy or breastfeeding, gastrointestinal infection within the last 2 weeks, intake of corticosteroids or antiemetics within the last week before surgery, known cardiac arrhythmia or therapy with antiarrhythmics grade II or III, fever (> 37.5°C), renal (creatinine > 1.4 mg%) and/or hepatic disease (glutamate‐oxaloacetate‐transaminases > 40 U/L and or glutamate‐pyruvate‐transaminases > 40 U/L); disease of the nervous system, addiction 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 Dolasetron Dose: 50 mg Time point of administration: with premedication Route of administration: PO Rescue antiemetics (if yes, which?): 20% (droperidol 1.25 mg IV) Dolasetron + dexamethasone Dose: dolasetron 50 mg, dexamethasone 8 mg Time point of administration: dolasetron with premedication, dexamethasone after induction of anaesthesia Route of administration: dolasetron: PO, dexamethasone: IV Rescue antiemetics (if yes, which?): 9.3% (droperidol 1.25 mg IV)
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome Vomiting (0 to 2 hours) Outcome type: dichotomous outcome Nausea (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: drugs were provided by Aventis Deutschland GmbH, Bad Soden, Deutschland. There was no other sponsorship Country: Germany Setting: inpatient, single‐centre Author's name: S.N. Piper Institution: Klinik für Anästhesiologie und Operative Intensivmedizin, Klinikum Ludwigshafen Email: swen.n.piper@t‐online.de Address: Klinik für Anästhesiologie und Operative Intensivmedizin, Klinikum Ludwigshafen, Bremserstraße 79, 67063 Ludwigshafen Duration of study: NA Language: German (2 German reviewers) Study's primary outcome: incidence of PONV Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "mit einer Randomisierungsliste wurden die Patientinnen einer der folgenden Gruppen zugeteilt" Judgement comment: sequence generation by random number tables
Allocation concealment (selection bias)	Low risk	Quote: "der Einschluss in die Studie erfolgte in Unkenntnis der Gruppenzuteilung" Judgement comment: inclusion of participants into the study without knowledge of group allocation
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "in Unkenntnis der Gruppenzuteilung. Weder dem Anästhesisten, der die Narkose durchführte und die i.v.‐ Studienmedikation verabreichte, noch dem Aufwachraumpersonal, noch dem Personal auf Normalstation war bekannt, welche Medikation die Patientin erhalten hatte. Alle Patientinnen hatten eine Nah..." Judgement comment: anaesthetists were blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "in Unkenntnis der Gruppenzuteilung. Weder dem Anästhesisten, der die Narkose durchführte und die i.v.‐ Studienmedikation verabreichte, noch dem Aufwachraumpersonal, noch dem Personal auf Normalstation war bekannt, welche Medikation die Patientin erhalten hatte. Alle Patientinnen hatten eine Nah..."
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: "zwischen den beiden Patientengruppen bestanden bezüglich demographischer und perioperativer Daten keine signifikanten Unterschiede (Tabelle 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