Doran 1980

Methods	Type of study: RCT Method of treatment allocation: method of randomisation not stated. Coded drug boxes were provided. Randomisation code was kept on file at the Pharmacy Department of Toronto General Hospital. Stratification: yes, by gestational age into 2 subgroups; 24‐32 weeks and 33‐34 weeks Placebo: yes, vehicle of steroid preparation consisting of 0.2 mg benzalkonium chloride and 0.1 mg disodium edentate per mL Sample size calculation: no Intention‐to‐treat analyses: yes Losses to follow‐up: no Funding: The Hospital for Sick Children Foundation, Canada; Schering Corporation, Canada; Ontario Ministry of Health Provincial Research Grant PR 279, Canada
Participants	Location: 6 teaching hospitals in Toronto, Canada Timeframe: January 1975‐June 1978 Eligibility criteria: women with PROM, spontaneous preterm labour or planned preterm delivery Gestational age range: 24 and 34 weeks. Exclusion criteria: women with pre‐eclampsia or in whom steroids were contraindicated on medical grounds. Total recruited: 137 women and 144 infants; 75 women and 81 infants in the treatment arm and 62 women and 63 infants in the control arm
Interventions	4 doses of 3 mg betamethasone acetate and 3 mg betamethasone sodium phosphate IM 12 h apart Control group received 4 doses of identical placebo
Outcomes	Fetal/neonatal outcomes were reported (fetal death, neonatal death, RDS, IVH, birthweight, days of mechanical ventilation)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomisation not stated
Allocation concealment (selection bias)	Low risk	Coded drug boxes were provided. Randomisation code was kept on file at the Pharmacy Department of Toronto General Hospital.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	It is likely that participants were blinded as both placebo and corticosteroid solutions were identical. Blinding of study personnel was not described other than to state "double blind".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding of outcome assessors was not described, but is likely as the authors state "The key to the code was not broken until the whole study was completed".
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up
Selective reporting (reporting bias)	Low risk	Study protocol not available, but appears to report on all pre‐specified outcomes
Other bias	Unclear risk	Insufficient information to asses if other sources of bias exist