Donaldson 2003.

Study characteristics
Methods	Randomised, double‐blind trial
Participants	Study period: January 1999 to December 1999 Setting: emergency department of William Beaumont Hospital, USA Inclusion criteria: children aged 3 to 84 months with history of inspiratory stridor or a barky cough and a Westley croup score of ≥ 2 after 10 to 15 minutes of cool mist therapy in the emergency department Exclusion criteria: Westley croup score < 2; signs suggesting another cause for stridor such as epiglottitis, bacterial tracheitis, foreign body, chronic lung disease; severe comorbidities; inability of parents to give informed consent; glucocorticoid therapy within 4 weeks of presenting Baseline demographics (N = 96): proportion male: treatment 1: 73%; treatment 2: 57% mean (SD) age in months: treatment 1: 23.2 (17.9); treatment 2: 28.9 (17.7) mean (SD) Westley croup score: treatment 1: 3.5 (1.8); treatment 2: 3.5 (1.7)
Interventions	Treatment 1 (N = 49): 0.60 mg/kg intramuscular dexamethasone and oral placebo (syrup) Treatment 2 (N = 46): 0.60 mg/kg oral dexamethasone and intramuscular placebo (direct pressure with hub of syringe on thigh)
Outcomes	Unscheduled revisits; parent‐reported symptom relief after 24 hours; use of epinephrine
Notes	Funding source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "block randomization method from a random number generator performed by the department of Pharmacy"
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information provided to permit a judgement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "In both groups, neither the parents nor the treating physicians were present in the treatment room during the administration of medications"; "The emergency medicine faculty... were blinded to the route of administration of the drug"; "If the child vomited while in the ED, the treatment given was unblinded" Comment: blinding was attempted but could be broken if the child vomited whilst in the emergency department. Subjective outcomes
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: third‐party outcome assessor described as blinded. Because blinding of children and parents could have been broken, the assessors could have become unblinded during conversation with parents. Subjective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: intention‐to‐treat analysis used. 1% (N = 1) loss to follow‐up, unclear from which group
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol identified. All prespecified outcomes in the methods appeared in the 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