Table 1.

A hypothetical randomised trial

Trial component	Description
Eligibility criteria	Individuals aged 65 years or older admitted to a critical care unit with severe pneumonia requiring intubation who have received 5 days of mechanical ventilation and cannot yet be liberated from the ventilator.
Treatment strategies	Immediate transition to comfort care measures. Immediate continuation of mechanical ventilation.*
Assignment procedures	Unblinded random assignment to one of the treatment strategies.
Follow-up period	Beginning at baseline, the time of randomisation, individuals are followed until death or the end of 30 days.†
Outcome	All-cause mortality by the end of 30-day follow-up.
Causal contrast of interest	Intention to treat effect.

*Note that these treatment strategies are not sustained because they only direct initial treatment. In other words, individuals assigned to ‘immediate continuation of mechanical ventilation’ may later be transitioned to comfort measures.

†For simplicity, we assume no loss to follow-up. This assumption is reasonable for ventilated patients for an endpoint at 30 days from randomisation.