Modir 2019.

Study characteristics
Methods	RCT
Participants	Women having elective CS under spinal anaesthesia N = 140
Interventions	Intervention 1: corticosteroid (Comparison 3) Dexamethasone N = ? Intervention 2: sedative (Comparison 6) Ketamine N = ? Intervention 3: (Comparison 6) Dexmedetomidine N = ? Comparator: placebo N = ?
Outcomes	Nausea and vomiting
Notes	Setting: Valiasr Hospital, Arak, Iran, presumably, but not stated specifically Dates: not reported Funding source: Arak University of Medical Sciences Declaration of interest: not reported. No data for the review as it is unclear how many women in each group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Block random allocation method used but no further details provided
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Although described as double blind ‐ no discussion of blinding participants or personnel
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: “… second project executive, who was unaware of the grouping assignment, recorded the data.”
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unclear how many women provided data in each group
Selective reporting (reporting bias)	Unclear risk	The same outcomes in the methods are reported in the results but we did not assess the trial protocol
Other bias	Unclear risk	Women were excluded (presumably after randomisation) if they were vomiting intra‐op or if dissatisfied – unclear why these women were to be excluded.