Feroci 2011.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Dexamethasone Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 51 Age (mean ± SD, median (IQR), median (range)): 53.8 ± 14.73 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 68.63 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 84.40 Use of perioperative opioids (if yes, which?): intraoperative remifentanil, no postoperative opioids Type of surgery: extracapsular total thyroidectomy or lobectomy Placebo Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 51 Age (mean ± SD, median (IQR), median (range)): 57.37 ± 13.15 Weight (mean ± SD, median (IQR), median (range)): NA BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): NA/NA/0/0 Gender (female in %): 66.67 Non‐smoker (%): NA History of PONV/motion sickness (%): NA Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 88.65 Use of perioperative opioids (if yes, which?): intraoperative remifentanil, no postoperative opioids Type of surgery: extracapsular total thyroidectomy or lobectomy Included criteria: underwent thyroid surgery for benign disease categorized as ASA I and II, weighed 50 kg to 100 kg Excluded criteria: younger than 18 years of age, previous malignant disease, previous thyroid surgery or neck surgery, had received antiemetic therapy within 48 hours before surgery, chronic pain disorder, insulin‐dependent diabetes mellitus, history of severe and/or repeated PONV after previous minor surgery, pregnancy Pretreatment: baseline characteristics (age, ASA): no; (weight): unclear. Potential effect modifiers (gender, duration of anaesthesia): no; (history of PONV/motion sickness, non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Dexamethasone Dose: 8 mg Time point of administration: 20 minutes before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): first‐line 10 mg/2 mL metoclopramide IV up to 3 times a day; second‐line 4 mg ondansetron IV up to 3 times a day Placebo Dose: NaCl Time point of administration: 20 minutes before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): first‐line 10 mg/2 mL metoclopramide IV up to 3 times a day; second‐line 4 mg ondansetron IV up to 3 times a day
Outcomes	Mortality (0 to 48 hours) Outcome type: dichotomous outcome Postoperative wound infection (0 to 30 days) Outcome type: dichotomous outcome
Identification	Sponsorship source: NA Country: Italy Setting: inpatient, single‐centre Author's name: Francesco Feroci Institution: General Surgery Unit, Misericordia and Dolce Hospital, Prato, Italy Email: fferoci@yahoo.it Address: NA Language: English Duration of study: January to December 2009 Trial registry number: NCT00888303 Study's primary outcome: primary outcome measure was PONV
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomization was performed by a computer‐generated list of random numbers"
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "identical syringes were prepared by staff who were not involved in the study according to the random number list. The patients, anesthetists, and investigators who collected the postoperative data were blinded to the randomization process and to the types of drugs administered"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "investigators who collected the postoperative data were blinded to the randomization process and to the types of drugs administered"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "between January 2009 and December 2009, 114 patients underwent surgery for thyroid disease at our institution. Ten patients were excluded from the randomization according to the following exclusion criteria: 2 patients who had a previous malignant disease, 2 patients who had undergone previous thyroid surgery, 4 patients who had insulin‐dependent diabetes mellitus, and 2 patients because of the lack of any comprehension of the Italian language. Two patients in the control arm were excluded from all analyses due to a postoperative hemorrhage requiring an urgent reparative operation. Therefore, data from 102 patients (51 for each group) were available for the analysis per protocol. One other patient in the dexamethasone group was excluded from subjective voice function analysis due to a verified lesion on the recurrent laryngeal nerve"
Selective reporting (reporting bias)	Unclear risk	Judgement comment: NCT00888303 (retrospective registration)
Other bias	Unclear risk	Quote: "there were no statistically significant differences between the 2 groups with regard to patient demographics, operation type, postoperative morbidity, and length of stay (Table 1)" Judgement comment: baseline characteristics (age, ASA): no; (weight): unclear. Potential effect modifiers (gender, duration of anaesthesia): no; (history of PONV/motion sickness, non‐smoker, perioperative opioids): unclear