Jepsen 1992

Methods	n = 66, 1 centre Allocation concealment: not described Baseline similarity: age Blinding: caregivers Cointerventions: corticosteroid administration "no different" between groups Withdrawals: none Losses to follow‐up: none
Participants	Inclusions: Risk factor for ARDS; PaO2 < 55 mmHg on room air or P/F < 250 mmHg; duration of intubation < 24 hours Exclusions: Chronic lung, cardiovascular, liver or renal disease
Interventions	IV NAC, bolus 150 mg/kg, then 20 mg/kg/hour continuously for 7 days (total dose 3510 mg/kg), or placebo
Outcomes	60 day mortality: RR 1.06 (95% CI 0.67 to 1.70) Adverse events leading to discontinuation of therapy: treatment: 1/32 (rash), control: 0/34
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear