Wang 2001.

Study characteristics
Methods	RCT
Participants	175 ASA 1‐2 women (body wt 50‐90 kg) undergoing elective CS under epidural anaesthesia without a history of PONV, GI disorder.
Interventions	Intervention 1: steroid (Comparison 3) Dexamethasone 2.5 mg. IV N = 44. Intervention 2: steroid (Comparison 3) Dexamethasone 5 mg. IV N = 44. Intervention 3: steroid (Comparison 3) Dexamethasone 10 mg IV N = 43. Comparison: placebo Placebo. IV N = 44.
Outcomes	Incidence of nausea, vomiting, severe vomiting (> 4 episodes), rescue antiemetics, total proportion with no nausea or vomiting.
Notes	Setting: Taipei, Taiwan. Dates: not reported. Funding source: not reported. Declaration of interest: not reported. Dose groups combined to yield overall treatment effect for dexamethasone (steroid). Drugs are in separate subgroups but then pooled in our analysis, so the placebo data are dealt with according to our methods (Unit of analysis issues)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "The randomisation process and the identity of the study drugs were blinded from the parturients, the anesthesiologists during surgery, and the investigators who collected the postoperative data".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "The randomisation process and the identity of the study drugs were blinded from the parturients, the anesthesiologists during surgery, and the investigators who collected the postoperative data".
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	5 excluded for missing data.
Selective reporting (reporting bias)	Unclear risk	We did not assess the trial protocol.
Other bias	Low risk	Baseline data similar.