Table 1.

Summary of economic evaluation framework

Question	Is the use of probiotics as compared with standard care without probiotics cost-effective for the prevention of VAP and other clinically important outcomes in critically ill medical-surgical patients in PROSPECT?
Perspective	Public payer (in-hospital costs)
Setting	Ventilated ICU patients (44 centres, 3 countries: 41 Canada, 2 USA, 1 Saudi Arabia)
Comparators	Probiotics (Lactobacillus rhamnosus GG) with usual care vs usual care without probiotics
Time horizon	From ICU participant admission to hospital discharge/death (non-fixed time span)
Discount rate	No discounting (no long-term follow-up over 1 year)
Clinical outcomes	VAP, CDAD, AAD, length of stay and mortality (ICU and hospital)
Costs	Direct medical costs associated with treatment and complications (ICU and ward costs, personnel, medications, laboratory tests, diagnostic testing and procedures/surgeries)
Evaluation	Primary outcome: incremental cost-efficacy ratios (ICERs) per in-hospital VAP event avoided Secondary outcomes: ICERs for other clinically important outcomes: Incremental cost per CDAD avoided Incremental cost per AAD avoided Incremental cost per death avoided
Currency (price date)	US dollars (2019)
Uncertainty	Non-parametric bootstrapping to produce confidence intervals Cost sampling from various hospitals (stratified by location) Sensitivity analyses to deal with structural and methodological uncertainty

AAD, antibiotic associated diarrhoea; CDAD, Clostriodiodes difficile–associated diarrhoea; ICER, incremental cost-efficacy/effectiveness ratio; ICU, intensive care unit; PROSPECT, Probiotics: Prevention of Severe Pneumonia and Endotracheal Colonization Trial; VAP, ventilator-associated pneumonia.