Jaung 2020.

Study characteristics
Methods	RCT, multicentre; 4 clinical sites, international (New Zealand and Australia), from December 2015 to May 2019
Participants	180 patients randomised in no‐AB (95, 1 withdrawal) and AB (85, 1 withdrawal) Inclusion: Left‐sided, CT‐verified diverticulitis, Hinchey 1a uncomplicated diverticulitis Exclusion: > 1 criterion for systemic inflammatory response syndrome upon presentation to hospital (temperature < 36°C or > 38° C, heart rate > 90 beats/min, respiratory rate > 20 breaths/min or PaCO2 < 32 mmHg, white cell count < 4 or > 12 109/L), unable to give consent or answer symptom‐related questions due to language barrier or cognitive impairment, previous drug reactions to the antibiotics used, lactose allergy, used steroids for > 5 days prior to presentation, administered regular immunomodulators or biologics within the 6 months prior to presentation, NSAID > 1 week prior to presentation, administered > 1 dose of IV or > 2 doses of oral AB during this illness but prior to enrolment in the study, pregnancy, ASA > 3, CT‐verified complicated acute diverticulitis, could not start taking the study medication within 24 hours of their admission into hospital
Interventions	Placebo‐controlled, double‐blinded, comparing AB with placebo Intervention: AB‐group: Initially IV cefuroxime 750 mg every 6 hours and oral metronidazole 400 mg 3 times a day and oral antibiotics amoxicillin/clavulanic acid 625 mg 3 times a day Control: No‐AB‐group: placebo Participants were prescribed the intravenous or oral regimen at the discretion of the surgical team, with a minimum treatment duration of 5 days of the oral regimen and a maximum treatment duration of 48 hours for the IV regimen and 5 days for the oral regimen (a total of 7 days of study medication). Participants requiring longer durations of treatment were regarded as having delayed recovery and started on conventional management, which included antibiotics. Participants were discharged when they were afebrile on oral study medication, able to tolerate oral diet, able to manage pain exclusively with oral analgesia, and able to mobilise safely and manage their activities of daily living. The final decision on discharge was made by the clinical team who were blinded to allocation status.
Outcomes	Primary: Length of hospital admission in hours from registration in emergency department to discharge into the community  Secondary: 1. Participant dropout or withdrawal rate 2. Occurrence af adverse events 3. Readmission within 1 week  4. Readmission within 30 days  5. Procedural intervention  6. Mortality  7. Change in serum markers of inflammation  8. Patient‐reported pain score at 12 and 24 hours
Notes	Rebekah Jaung is a doctoral candidate funded by the Auckland Medical Research Foundation, and the STAND study was funded by a project grant from the Colorectal Surgical Society of Australia and New Zealand. The authors disclosed no conflicts.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐based random number generator. Randomisation was blocked into groups of 4 to ensure a comparable allocation to treatment and control groups.
Allocation concealment (selection bias)	Low risk	Allocation performed by the external pharmacy where the study medications were manufactured.
Blinding (performance bias and detection bias) All outcomes	Low risk	Participants, study investigators, and clinical staff were blinded to treatment allocation. The antibiotics and placebo were packaged in identical vials and bottles and labelled with a study identification number.
Incomplete outcome data (attrition bias) All outcomes	Low risk	180 participants were randomised; 0 were excluded after randomisation. 3 participants were lost to follow‐up (AB: 2 vs. placebo: 1). In total, 3 participants did not complete the trial corresponding to an attrition rate of 1.7% which was acceptable and reasons for exclusion were justified. Group sizes with α = 0·05 and a power of 99 per cent were calculated and reported to be 262 in each group which gave sufficient power.
Selective reporting (reporting bias)	Low risk	Method and outcomes were specified and were available during the study period on clinicaltrials.gov, Jaung 2015