Table 1 Primary, secondary and other objectives and measures in the main trial

To compare the effect of introducing the behavioural intervention on 30-day mortality post-admission as an acute/general medical inpatient (non-inferiority)

Death, ascertained from hospital records which are routinely updated from national death reporting

30 calendar days after admission to acute/general medicine

To compare the effect of introducing the behavioural intervention on antibiotic exposure per acute/general medical admission (superiority)

Defined daily doses (DDDs) of antibiotics per acute/general medical admission, ascertained from electronic hospital prescribing records

Over each acute/general medical admission, including antibiotics prescribed at discharge

To compare the effect of introducing the behavioural intervention on antibiotic exposure using different metrics

DDD per occupied bed-day, days on antibiotics per admission and bed-day (length of therapy (LOT)),^a antibiotic days per admission and bed-day (days of therapy, DOT^a), carbapenem DDD, DOT^a and LOT^a (per admission and per bed-day), broad-spectrum DDD, DOT^a and LOT^a (per admission and per bed-day), IV and oral DDD, DOT^a and LOT^a (per admission and per bed-day), WHO-defined ’Access’, ’Watch’ and ’Reserve’ DDD, DOT^a and LOT^a (per admission and per bed-day), ’Access’ as a percentage of all antibiotic use

Over each acute/general medical admission, including antibiotics prescribed at discharge

To compare the effect of introducing the behavioural intervention on adverse outcomes

ICU admission during the current admission, total length of stay (hours), antibiotic restart after discontinuation,^a emergency re-admission in the 30 days after discharge, C. difficile diarrhoea, mortality over the longer term

ICU admission over the current admission; for emergency re-admission, up to 30 days post-discharge; for C. difficile diarrhoea, up to 90 days post-admission; for mortality up to 90 days post-admission

To evaluate the impact of the intervention on the faecal flora

Proportion of discarded faecal samples from medical inpatients from which extended spectrum beta-lactamase (ESBL)-carrying Enterobacteriaceae can be isolated

Repeated cross-sectional surveys over time

To evaluate the cost-effectiveness of the behavioural intervention

Resource utilisation and costs

Over the current admission and up to 30 days post-discharge

To quantify uptake and acceptability of the online training component of the behavioural intervention (process outcome)

Proportion of locally identified and pre-specified essential individuals who drive prescribing decisions for acute/general medical inpatients at the organisation who complete the online training (recorded electronically by individuals entering their name and work (NHS) email on the last page) or on an attendance list if the local organisation has opted to do face-to-face training sessions

Within 3 months of invitation to complete training

To quantify uptake of the ARK ‘review and revise’ procedure within the behavioural intervention (process outcome)

Proportion of regularly audited antibiotics prescriptions which document the ARK classification criteria

Proportion of regularly audited antibiotics prescriptions which are stopped at ‘review and revise’

Over 12 weeks following implementation date