Martinez Fernandez 1993.

Methods	Randomised double‐blind controlled trial
Participants	Study period: October 1989 to September 1990 Setting: Children's Hospital in Spain Inclusion criteria: children hospitalised with symptoms suggestive of croup (acute laryngitis, laryngotracheobronchitis, spasmodic croup) Exclusion criteria: child's croup judged by the physician to be too severe Baseline characteristics (N = 66): proportion males: not reported age: not reported mean (SD) croup score: treatment 1: 3.5 (1.7); treatment 2: 2.9 (1.4); treatment 3: 3.3 (1.1); control: 3.2 (1.5)
Interventions	Treatment 1 (N = 15): single dose of intramuscular placebo, plus 0.14% nebulised L‐epinephrine initially and every 4 hours as needed Treament 2 (N = 16): single 0.5 mg/kg dose of intramuscular dexamethasone, plus nebulised placebo (saline) initially and every 4 hours as needed Treatment 3 (N = 18): single 0.5 mg/kg dose of intramuscular dexamethasone, plus 0.14% nebulised L‐epinephrine initially and every 4 hours as needed Control (N = 17): single dose of intramuscular placebo, plus nebulised placebo (saline) initially and every 4 hours as needed All children received humidified oxygen and fluid therapy.
Outcomes	Change in croup score from baseline to 6, 12, and 24 hours
Notes	Written in Spanish; 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)	Low risk	Comment: treatments shipped in pre‐numbered ampoules, unlabeled and randomly ordered by the pharmacy.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Comment: described as double‐blind. Treatments shipped in pre‐numbered ampoules, unlabeled and randomly ordered by the pharmacy.
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.