Joo 2015.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 3 groups, monoprophylaxis and combination prophylaxis
Participants	Baseline characteristics Dexamethasone Assessed for eligibility (n): NA Enrolled (n): NA Randomized (n): 50 Received treatment (n): 50 Analysed (n): 50 Age (mean ± SD, median (IQR), median (range)): 40 (20 to 60) Weight (mean ± SD, median (IQR), median (range)): 56.9 ± 5.7 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 40/10/0/0 Gender (female in %): 100% Non‐smoker (%): 100% History of PONV/motion sickness (%): 52% Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 150.3 Use of perioperative opioids (if yes, which?): 104.7 µg remifentanil, 470.1 µg fentanyl via PCA Type of surgery: gynaecological laparoscopic surgery Haloperidol 1 mg + dexamethasone Assessed for eligibility (n): NA Enrolled (n): NA Randomized (n): 50 Received treatment (n): 50 Analysed (n): 49 Age (mean ± SD, median (IQR), median (range)): 39 (20 to 60) Weight (mean ± SD, median (IQR), median (range)): 55.0 ± 7.9 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 41/8/0/0 Gender (female in %): 100% Non‐smoker (%): 100% History of PONV/motion sickness (%): 57% Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 157.9 Use of perioperative opioids (if yes, which?): 97.2 µg remifentanil, 465.6 µg fentanyl via PCA Type of surgery: gynaecological laparoscopic surgery Haloperidol 2 mg + dexamethasone Assessed for eligibility (n): NA Enrolled (n): NA Randomized (n): 50 Received treatment (n): 50 Analysed (n): 50 Age (mean ± SD, median (IQR), median (range)): 41 (21 to 58) Weight (mean ± SD, median (IQR), median (range)): 54.4 ± 5.3 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 39/11/0/0 Gender (female in %): 100% Non‐smoker (%): 100% History of PONV/motion sickness (%): 56% Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 156.4 Use of perioperative opioids (if yes, which?): 92.5 µg remifentanil, 467.8 µg fentanyl via PCA Type of surgery: gynaecological laparoscopic surgery Included criteria: ASA I or II, female, 20 to 65 years of age, scheduled for gynaecologic laparoscopic surgery and intravenous (IV) PCA for postoperative pain control. Based on Apfel’s simplified risk score, patients in this study had the following 3 standard PONV risk factors: female, non‐smoker, and use of opioid analgesics after surgery Excluded criteria: known allergy or intolerance to study drug; history of cardiac arrhythmia; psychiatric illness; long‐term treatment with a dopamine antagonist; use of opioids or steroids within 1 week of surgery; use of antiemetic in the 24 hours before the study; inability to use the PCA device; gastrointestinal, renal, or hepatic disease; insulin‐dependent diabetes or obesity, body mass index > 35 kg/m² Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of PONV/motion sickness, perioperative opioids): no
Interventions	Intervention characteristics Dexamethasone Dose: 5 mg Time point of administration: dexamethasone at induction, placebo 30 minutes before end of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): 30% (ondansetron 4 mg) Haloperidol 1 mg + dexamethasone Dose: dexamethasone 5 mg, haloperidol 1 mg Time point of administration: dexamethasone at induction, haloperidol 30 minutes before end of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): 11% (ondansetron 4 mg) Haloperidol 2 mg + dexamethasone Dose: dexamethasone 5 mg, haloperidol 2 mg Time point of administration: dexamethasone at induction, haloperidol 30 minutes before end of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): 10% (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 Arrhythmia (PACU) Outcome type: dichotomous outcome Extrapyramidal symptoms (0 to 24 hours) Outcome type: dichotomous outcome
Identification	Sponsorship source: departmental resources only. No sponsor involvement Country: Korea Setting: inpatient, single‐centre Author's name: Young Eun Moon Institution: Department of Anesthesiology and Pain Medicine, Seoul St.Mary´s Hospital, College of Medicine, The Catholic University of Korea Email: anemoon@naver.com Address: 222 Banpo‐daero, Seocho‐gu, Seoul 137‐701, Republic of Korea Language: English Duration of study: NA Trial registry number: NCT01639599 Study's primary outcome: incidence of PONV in 24 hours
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "computer‐generated codes"
Allocation concealment (selection bias)	Unclear risk	Quote: "using computer‐generated codes placed in sequentially numbered, opaque envelopes, the enrolled patients were assigned randomly to one of three groups" Judgement comment: not stated; "sealed" envelopes (SNOSE)
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "a nurse anesthetist not involved in the treatment opened the envelopes and prepared the study drugs in identical syringes with a total volume of 2 mL (diluted with saline). The patients and attending anesthesiologists were blinded to the group assignments"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "staff who remained blind to the group assignment made the postoperative evaluations"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "of the 150 patients registered for the study, one was excluded due to an intra‐operative conversion to laparotomy (Fig. 1). The remaining 149 patients, consisting of 50, 49, and 50 patients in groups H0, H1, and H2, respectively, completed the study"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: NCT01639599 (retrospective registration)
Other bias	Low risk	Judgement comment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of PONV/motion sickness, perioperative opioids): no