UK data suggests that current treatment for complicated intra-abdominal infections (cIAIs) results in unacceptably high rates of cIAI relapse and extra-abdominal infection. As a guiding rule, shorter antibiotic durations are important to combat antimicrobial resistance, but this is not true when these shorter courses need repeating and result in more days in hospital. Optimal care for patients should be our primary concern.~The EXTEND trial aims to find out whether a fixed extended duration of 28 days of antibiotics is superior to the current standard duration (typically 7-18 days) based on clinical outcomes and quality of life assessed over 180 days of follow up. Cost effectiveness will also be determined.~A target of 1166 patients will be recruited from ICUs and hospital in-patient wards across 30 NHS trust hospitals. Only patients that provide consent (or a consultee provides consent on their behalf) can take part in the trial. They will receive antibiotics as prescribed by their treating clinician, but the duration of treatment will be determined by randomisation. Patients will have equal chance of randomisation to the standard care arm, in which the antibiotic duration will be determined by the treating clinician, or the intervention arm, a fixed duration of 28 days treatment.~Patients (or a personal consultee) will complete a quality of life questionnaire at baseline and 30, 60 and 180 days after randomisation. At follow-up timepoints they will also complete questionnaires on antibiotic use and health care resource use. Hospital notes will be used to collect data on inpatient admissions, relapse and further infections.
A multicentre, open label, two-arm, parallel group, pragmatic, randomised controlled trial with internal pilot. A total of 1166 consenting adult patients with cIAI will be recruited and randomised on a 1:1 basis between 28-days antibiotics and standard care antibiotics. Patients will be followed up for 180 days to determine cost effectiveness and the rate of treatment failure in each group.