D'Agostino 2000.

Methods	Single‐centre parallel‐group randomized controlled trial conducted in USA
Participants	40 2‐months – 8‐year‐old children requiring neuroimaging with sedation. Average age 31 ± 23 months and 45% were boys.
Interventions	Oral midazolam 0.5 mg/kg (max 10 mg) vs oral chloral hydrate 75 mg/kg (max 2 g) Could received additional dose (50% of original dose) if required
Outcomes	Measured during the procedure: 1) Numerical rating of anxiety 2) Duration of sedation 3) Incomplete procedures
Notes	Conflicts of interest or funding sources were not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random‐number table
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Children were administered freshly‐prepared, identically‐appearing, cherry‐flavoured liquids in body weight equivalent volumes
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Neither the participant nor any of the investigators were aware of the active component given to individual participants
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reasons for withdrawals were reported. Randomized children who did not complete the protocol included 1 with respiratory distress, 1 who ate a full meal prior to intended drug administration, 1 who fell asleep after intravenous line placement and 4 who cancelled their appointments after randomization
Selective reporting (reporting bias)	Unclear risk	No clear evidence that measured outcomes were not reported (trial protocols were not sought for confirmation)
Other bias	Low risk	None expected