Chub‐Uppakarn 2007.

Methods	Randomised double‐blind controlled trial
Participants	Study period: March 2001 to October 2003 Setting: paediatric ward of Hatyai Hospital in the southern part of Thailand Inclusion criteria: children aged 6 months to 5 years who were admitted to the paediatric ward with moderate to severe croup. Westley croup score 4 to 7 Exclusion criteria: history of contact with chicken pox within the preceding 3 weeks; history of congenital or acquired stridor; chronic pulmonary disease; asthma; severe systemic disease or known immune dysfunction; treatment with corticosteroids within the preceding 2 weeks; treatment with epinephrine for respiratory distress before enrolment Baseline demographics (N = 41): proportion male: treatment 1: 55%; treatment 2: 86% mean (SE) age in months: treatment 1: 16.9 (2.0); treatment 2: 18.8 (2.6) mean (SD) Westley croup score: treatment 1: 4.26 (0.22); treatment 2: 4.60 (0.25)
Interventions	Treatment 1 (N = 21): single 0.15 mg/kg dose (maximum 3 mg) of intramuscular dexamethasone Treatment 2 (N = 20): single 0.60 mg/kg dose (maximum 12 mg) of intramuscular dexamethasone
Outcomes	Change in Westley croup score at 2, 6, and 12 hours; intubations; adverse events
Notes	All children were treated with a single nebulisation of epinephrine (1:1000) 1 mL in 0.9% saline 3 mL at baseline. Funding source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "computer‐generated randomization scheme used random permuted blocks of four children"
Allocation concealment (selection bias)	Low risk	Quote: "codes were secured at the hospital pharmacy until enrolment and all decisions regarding data analysis had been finalized"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "the preparations of dexamethasone suspension consisted of 10 mL of dexamethasone phosphate injection in concentrations of 1.2 and 0.3 mg/mL The preparations were packaged in identical containers by a hospital pharmacist and were not distinguishable in appearance"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: no description of a third‐party outcome assessor. Carried over judgement from blinding of participants and personnel
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: no missing outcome data
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol identified. All prespecified outcomes from methods appear in results.
Other bias	Low risk	Comment: no other sources of bias identified.
Overall risk of bias All outcomes	Unclear risk	Comment: at least 1 domain judged as unclear risk, and no domains judged as high risk.