Ibrahim 2013.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 4 groups, monoprophylaxis, dose‐finding study
Participants	Baseline characteristics Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 21 Received treatment (n): NA Analysed (n): 21 Age (mean ± SD, median (IQR), median (range)): 42 ± 13 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 25 ± 5 ASA I/II/III/IV (n): 12/9/0/0 Gender (female in %): 100 Non‐smoker (%): 80.95 History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: balanced anaesthesia (sevoflurane, N₂O, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 107 Use of perioperative opioids (if yes, which?): 1.8 µg/kg intraoperative fentanyl Type of surgery: breast surgery (mastectomy, tumour biopsy, reductive mastoplasty, other plastic surgery) Olanzapine (5 mg group) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 21 Received treatment (n): NA Analysed (n): 21 Age (mean ± SD, median (IQR), median (range)): 41 ± 14 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 26 ± 4 ASA I/II/III/IV (n): 10/11/0/0 Gender (female in %): 100 Non‐smoker (%): 76.19 History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: balanced anaesthesia (sevoflurane, N₂O, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 103 Use of perioperative opioids (if yes, which?): 2.0 µg/kg intraoperative fentanyl Type of surgery: breast surgery (mastectomy, tumour biopsy, reductive mastoplasty, other plastic surgery) Olanzapine (10 mg group) Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 43 ± 12 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 27 ± 4 ASA I/II/III/IV (n): 12/8/0/0 Gender (female in %): 100 Non‐smoker (%): 75 History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: balanced anaesthesia (sevoflurane, N₂O, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 110 Use of perioperative opioids (if yes, which?): 2.1 µg/kg intraoperative fentanyl Type of surgery: breast surgery (mastectomy, tumour biopsy, reductive mastoplasty, other plastic surgery) Ondansetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): 20 Received treatment (n): NA Analysed (n): 20 Age (mean ± SD, median (IQR), median (range)): 42 ± 12 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): 26 ± 5 ASA I/II/III/IV (n): 11/9/0/0 Gender (female in %): 100 Non‐smoker (%): 85 History of PONV/motion sickness (%): NA/0 Type of general anaesthesia: balanced anaesthesia (sevoflurane, N₂O, fentanyl) Duration of anaesthesia or surgery (in min; as mean or median): 105 Use of perioperative opioids (if yes, which?): 1.9 µg/kg intraoperative fentanyl Type of surgery: breast surgery (mastectomy, tumour biopsy, reductive mastoplasty, other plastic surgery) Included criteria: females scheduled for breast surgery (mastectomy, tumour biopsy, reductive mastoplasty, other plastic surgery), ASA I or II Excluded criteria: pre‐existing nausea, vomiting, or motion sickness; receiving opioids or drugs with known antiemetic properties in the 24 hours before surgery; history of oesophageal reflux or opioid or alcohol abuse; serum creatinine > 2.0 mg/dL; serum alanine aminotransferase (ALT) or aspartate transaminase (AST) > 2 times the upper limit of normal; body weight twice the ideal body weight Pretreatment: baseline characteristics (age, BMI, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of motion sickness): no; (history of PONV): unclear
Interventions	Intervention characteristics Placebo Dose: sugar pills Time point of administration: 4 hours and 1 hour before induction Route of administration: PO Rescue antiemetics (if yes, which?): NA Olanzapine (5 mg group) Dose: 5 mg Time point of administration: 4 hours before induction of anaesthesia, placebo 1 hour before induction Route of administration: PO Rescue antiemetics (if yes, which?): NA Olanzapine (10 mg group) Dose: 10 mg Time point of administration: 4 hours before induction of anaesthesia, placebo 1 hour before induction Route of administration: PO Rescue antiemetics (if yes, which?): NA Ondansetron Dose: 16 mg Time point of administration: 1 hour before induction of anaesthesia, placebo 4 hours before induction Route of administration: PO Rescue antiemetics (if yes, which?): NA
Outcomes	Vomiting (0 to 2 hours) Outcome type: dichotomous outcome Vomiting (2 to 24 hours) Outcome type: dichotomous outcome Subjects with any SAE (0 to 24 hours) Outcome type: dichotomous outcome Arrhythmia (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: NA Country: Egypt Setting: inpatient, single‐centre Author's name: Mohamed Ibrahim Institution: Department of Anaesthesia, Zagazig University, Egypt Email: mibrahim72@windowslive.com Address: Palestine Madina Road, P.O. Box 7692, Jeddah 21472, Saudi Arabia Duration of study: NA Language: English Study's primary outcome: emetic episodes and occurrence of nausea Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly allocated to one of four groups" Judgement comment: no further information on sequence generation provided
Allocation concealment (selection bias)	Unclear risk	Quote: "after a patient was assigned to a treatment group, the assignment was recorded and placed in a sealed envelope by a person not involved in the study. A pharmacist, who was also not involved in the study, prepared the study medications and sealed it in an envelope" Judgement comment: it is unclear how the allocation was done
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "to ensure blindness, placebo drug was given in OL5 and OL10 groups 1 h before induction and 4 h before induction in ON16. Placebo group of patients received sugar pills 4 and 1 h before induction" Quote: "a nurse or a physician, who was blinded to the patient treatment groups, gave the study drugs and recorded preoperative and postoperative data" Quote: "a pharmacist, who was also not involved in the study, prepared the study medication and sealed it in an envelope" Quote: "the trial arms in the study were blinded in spite of different olanzapine and ondansetron pharmacokinetics that affect time of drug administration"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "a nurse or a physician, who was blinded to the patient treatment groups, gave the study drugs and recorded preoperative and postoperative data"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "eighty‐two patients were included in the study" 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: "there were no significant differences in patients’ characteristics between treatment groups, including relation of surgery time with stage of menstrual cycle. The mean duration of anesthesia and duration of operation were not different. Also, no significant differences were noted among groups with respect to surgery type (Table 1)" Judgement comment: baseline characteristics (age, BMI, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, non‐smoker, history of motion sickness): no; (history of PONV): unclear