Godden 1997.

Methods	Randomised double‐blind controlled trial
Participants	Study period: November 1993 to April 1995 Setting: paediatric wards of Poole NHS Trust Hospital, Dorset, England Inclusion criteria: children admitted to hospital with a clinical diagnosis of croup based on the modified Westley croup score Exclusion criteria: receiving bronchodilators or received systemic steroids within the previous month Baseline demographics (N = 89): proportion male: treatment: 72%; control: 64% mean (range) age in months: treatment: 35.7 (7 to 116); control: 37.4 (7 to 93) mean (SD) modified Westley croup score (N = 87): treatment: 5.30 (3.44); control: 5.15 (3.70)
Interventions	Treatment (N = 47): initial 2 mg (4 mL) dose of nebulised budesonide, followed by a repeating dose of 1 mg every 12 hours Control (N = 42): initial 4 mL dose of nebulised placebo (normal saline), followed by a repeating dose of 2 mL placebo (normal saline) every 12 hours Both treatment and placebo delivered via an opaque nebuliser chamber, driven by wall oxygen at a rate of 8 L/min.
Outcomes	Change in modified Westley croup score from baseline to 2, 4, 12, and 24 hours; length of stay in hospital; use of epinephrine and intubation
Notes	Baseline croup score not presented for 2 children due to prior treatment with nebulised L‐epinephrine; funding source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: insufficient information provided to judge.
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information provided to judge.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "trial solution was supplied in an opaque respule within a sealed silver foil packet." "The patient initially received 4 mL of a solution containing either normal saline vehicle or 4mg (4mL) of budesonide, via an opaque nebuliser chamber."
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: 8% (N = 7) withdrew, equal between groups (9% in study group, 7% in control group).
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol identified. All prespecified outcomes from methods appear in results.
Other bias	Unclear risk	Comment: some possible participants were not enrolled due to manpower constraints, which could potentially have biased participant selection.
Overall risk of bias All outcomes	Unclear risk	Comment: at least 1 domain judged as unclear risk, and no domains judged as high risk.