Kuusela 1988.

Methods	Randomised double‐blind controlled trial
Participants	Study period: October 1984 to March 1985 and January 1986 to April 1986 Setting: Department of Paediatrics, Tampere University Central Hospital, Finland Inclusion criteria: children diagnosed and admitted for acute laryngitis (croup) Exclusion criteria: not reported Baseline demographics (N = 72): proportion males: treatment 1: 74%; treatment 2: 88%; treatment 3: 88%; control: 67% mean (SD) age in years: treatment 1: 2.9 (1.5); treatment 2: 2.3 (1.7); treatment 3: 2.8 (1.8); control: 3.2 (2.7) croup score: not measured
Interventions	All children received initial treatment in the emergency department, then were transferred to a ward where they were placed in a humid room and given oral fluids at a minimum of 20 mL/kg body weight over the next 4 hours. Treatment 1 (N = 19): single 0.6 mg/kg (0.12 mL/kg, maximum 2 mL) dose of intramuscular dexamethasone plus at least 1 0.25 mL/5 kg (maximum 1.5 mL) dose of nebulised L‐epinephrine (2.25% epinephrine base with 0.5% chlorobutanol as preservative). Additional doses of nebulised L‐epinephrine every 2 hours as needed Treatment 2 (N = 16): single 0.6 mg/kg (0.12 mL/kg, maximum 2 mL) dose of intramuscular dexamethasone plus at least 1 0.25 mL/5 kg (maximum 1.5 mL) dose of nebulised placebo solution. Additional doses of nebulised placebo every 2 hours as needed Treatment 3 (N = 16): single 0.6 mg/kg (0.12 mL/kg, maximum 2 mL) dose of intramuscular placebo plus at least 1 0.25 mL/5 kg (maximum 1.5 mL) dose of nebulised L‐epinephrine (2.25% epinephrine base with 0.5% chlorobutanol as preservative). Additional doses of nebulised L‐epinephrine every 2 hours as needed Control (N = 21): single 0.6 mg/kg (0.12 mL/kg, maximum 2 mL) dose of intramuscular placebo plus at least 1 0.25 mL/5 kg (maximum 1.5 mL) dose of nebulised placebo solution. Additional doses of nebulised placebo every 2 hours as needed
Outcomes	Change in clinical score based on dyspnoea and cough scale from baseline to 6, 12, and 24 hours; length of stay in hospital
Notes	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	Quote: "the ampules were unlabelled, numbered, and randomized; the code was not available for investigators until the end of the study"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "The placebo preparation consisted of the corresponding diluent supplied in similar ampules." "the code was not available for the investigators until the end of the study" "The active solution and the placebo preparation were identically packed in individual randomized vials containing 10 ml"
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	Unclear risk	Comment: did not use intention‐to‐treat analysis. 8% (N = 6) excluded due to protocol violations, unclear what group they were in.
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.