Table 1

Ambulance CPAP: Use, Treatment effect and Economics trial objectives and outcomes

Feasibility outcomesFeasibility targets
1.Rate of eligible patients per 100 000 population per year
  • Target 8 per 100 000 per year, that is, 120 across the 1.5 million population of the 4 hubs

2.Proportion recruited and allocated to treatment appropriately
  • Proportion recruited in error and classified as major or minor non-compliances (target 0% and ≤10%).

3.Adherence to allocated treatment
  • Adherence to the allocation schedule (target ≥90%)

  • Adherence to treatment in the CPAP arm (target ≥75%)

4.Retention and data completeness up to 30 days
  • Retention at 30 days (target ≥90%)

  • Data completeness (target ≥90%)

Clinical outcome measures
1. Proportion surviving to 30 days (primary outcome for definitive trial)
2. Proportion undergoing endotracheal intubation by 30 days
3. Proportion admitted to critical care at any point up to 30 days
4. Mean and median length of hospital stay
5. Change in Visual Analogue Scale dyspnoea score from presentation to immediately before ED arrival
6. Mean change in quality of life, measured with EQ-5D-5L
7. Key elements of postdischarge healthcare resource use up to 30 days
  • CPAP, continuous positive airway pressure ; EQ-5D-5L, EuroQOL-5D-5L Value Sets.