Leipzig 1979.

Study characteristics
Methods	Randomised, double‐blind controlled trial
Participants	Study period: November 1976 to March 1978 Setting: Pediatric Service of the State University Hospital or the Crouse‐Irving Memorial Hospital, Syracuse, NY, USA Inclusion criteria: all children admitted to hospital with a diagnosis of croup with disease of sufficient severity on a predetermined scoring system; consent of the child's physician and parents Exclusion criteria: not reported Baseline demographics (N = 30): proportion males: not reported mean age in months: treatment: 21.3; control: 21.0 mean (SD) croup score: treatment: 8.46 (1.45); control: 8.14 (1.46)
Interventions	Treatment (N = 16): 2, 0.30 mg/kg doses of intramuscular dexamethasone (4 mg/mL) Control (N = 14): 2 doses of intramuscular placebo (sterile saline) (1 dose initially and another 2 hours later)
Outcomes	Change in croup score from baseline to 24 hours; length of stay at hospital; intubation
Notes	Funding source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "assigned from a table of random numbers"
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: "Vials had been previously prepared containing either dexamethasone (4 mg/L) or sterile saline. They were marked only with a number, assigned from a table of random numbers" Comment: described as double‐blind. Unclear who was blinded and who prepared the vials. Subjective outcomes
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "Vials had been previously prepared containing either dexamethasone (4 mg/L) or sterile saline. They were marked only with a number, assigned from a table of random numbers" Comment: described as double‐blind. Unclear who was blinded and who prepared the vials. Subjective outcomes
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 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