Lee 2006.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): NA Analysed (n): 37 Age (mean ± SD, median (IQR), median (range)): 57.4 ± 12 Weight (mean ± SD, median (IQR), median (range)): 58.3 ± 7 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 35.14 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: inhalational anaesthesia Duration of anaesthesia or surgery (in min; as mean or median): 240.8 Use of perioperative opioids (if yes, which?): fentanyl via epidural infusor Type of surgery: subtotal gastrectomy Droperidol Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 40 Received treatment (n): NA Analysed (n): 35 Age (mean ± SD, median (IQR), median (range)): 54.8 ± 12 Weight (mean ± SD, median (IQR), median (range)): 59.7 ± 8 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 34.29 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: inhalational anaesthesia Duration of anaesthesia or surgery (in min; as mean or median): 254.4 Use of perioperative opioids (if yes, which?): fentanyl via epidural infusor Type of surgery: subtotal gastrectomy Included criteria: ASA I or II, diagnosed with cancer of the stomach, undergoing elective subtotal gastrectomy Excluded criteria: recent use of opioids; any cutaneous pathology with pruritus; administration of antiemetic medication within 24 hours before surgery; history of motion sickness, convulsion, parkinsonism, or psychiatric problems; inability to answer questions Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of motion sickness): no; (history of PONV, non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Placebo Dose: saline Time point of administration: on surgical commencement of skin closure Route of administration: epidural Rescue antiemetics (if yes, which?): metoclopramide 10 mg or ondansetron 4 mg IV Droperidol Dose: 2.5 mg Time point of administration: on surgical commencement of skin closure Route of administration: epidural Rescue antiemetics (if yes, which?): metoclopramide 10 mg or ondansetron 4 mg IV
Outcomes	Arrhythmia (0 to 48 hours) Outcome type: dichotomous outcome Adverse events (general notes in the publication, 48 hours' observation) Outcome type: general notes on side effects
Identification	Sponsorship source: NA Country: South Korea Setting: inpatient, single‐centre Author's name: Il Ok Lee Institution: Korea University College of Medicine, Guro Hospital, Department of Anesthesiology, Seoul, South Korea Email: iloklee@korea.ac.kr Address: Department of Anesthesiology, Guro Hospital, Guro ku Gurodong gil 97 Korea University College of Medicine, Seoul, South Korea 152‐703 Duration of study: March 2000 to October 2001 Language: English Study's primary outcome: incidence of PONV and pruritus Trial registry number: NA
Notes	Two out of 3 groups relevant (continuous infusion of droperidol)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "patients were randomly allocated to one of the following three groups (n 40 each) according to a random‐number table"
Allocation concealment (selection bias)	Unclear risk	Quote: "an independent pharmacist prepared three sets of 10 mL syringe and infusions (Infusor LV5; Baxter Healthcare Corp., USA) according to the Group A, B and C and these sets were kept concealed in numbered envelopes and all study personnel and participants were blinded to treatment assignment for the duration of the study" Judgement comment: not stated; "sequentially numbered, opaque, and sealed envelopes" (SNOSE)
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "all study personnel and participants were blinded to treatment assignment for the duration of the study"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "the severity of pruritus, PONV, pain and sedation were evaluated by an anaesthesiologist who was blinded to the study treatments at 1, 6, 24 and 48 h postoperatively"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "twelve patients were excluded. An epidural catheter could not be placed in seven patients for technical reasons and patient discomfort preoperatively, therefore epidural analgesia was placed postoperatively. In three patients who have shown far advanced gastric cancer during operation, gastrojejunostomy was performed instead of a gastrectomy. There were missing data from two patients. Data from the remaining 108 patients were analysed"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Quote: "all groups were demographically similar, and there were no differences in epidural levels or surgery duration (Table 1)" Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of motion sickness): no; (history of PONV, non‐smoker, perioperative opioids): unclear