Study	Reason for exclusion
Biondo 2014	Study description: Multicentre, randomised controlled trial, including patients with CT‐verified acute uncomplicated left‐sided diverticulitis. There were 2 strategies of management: hospitalisation (group 1) and outpatient (group 2). Both groups had the same antibiotic regimen. Reasons for exclusion: Investigating outpatient management and not observational versus antibiotic treatment
Colecchia 2007	Study description: Multicentre, open‐label, prospective, randomised study. Comparing rifaximin (400 mg for 7 days every month) plus dietary fibre supplementation (at least 20 g/day) and simply dietary fibre supplementation (at least 20 g/day). The study duration was 24 months. Reasons for exclusion: No distinction between acute diverticulitis and diverticular disease
Estrada 2016	Study description: Patients with mild acute diverticulitis with/or without comorbidities received outpatient treatment without antibiotics. Patients with moderate acute diverticulitis were admitted for 48 hours and then managed as outpatients; they received 10 days of antibiotics. Reasons for exclusion: Not a randomised controlled trial. Investigating outpatient management and not antibiotic treatment
Kim 2019	Study description: Single‐centre, open‐label, randomised controlled trial, investigating CT‐verified uncomplicated acute diverticulitis in the right‐sided colon. Participants were randomised to observational (bowel rest and IV fluids) and antibiotic (bowel rest, IV fluids, and antibiotics). Clinicians, the data manager, and participants were masked to treatment assignment. The primary outcome was the treatment failure, and secondary outcomes were the length of hospital stay and total admission costs. 61 participants vs. 64 participants. Concluded observational and antibiotic management of uncomplicated right‐sided colonic diverticulitis showed similar treatment failure rates and length of hospital stay. Observational management was associated with lower hospital costs, compared with standard antibiotic treatment. Therefore, observational management can be considered as a safe treatment option. Reasons for exclusion: investigating right‐sided colon
Ridgway 2008	Study description: randomised controlled trial, comparing intravenous versus oral antibiotic treatment Reasons for exclusion: Diagnosis was based on clinical symptoms only with no radiographic confirmation.
Schug‐Pass 2010	Study description: Randomised controlled trial comparing treatment with intravenous ertapenem for 4 days vs. 7 days in patients with CT/US‐verified diagnosis of uncomplicated acute diverticulitis. The primary outcome was successful treatment. Reasons for exclusion: All included participants were treated with the same intravenous treatment the first 4 days. Randomisation was performed on day 4, if treatment had been successful. Because the treatment had not been successful after 4 days, 17 participants were excluded from being randomised at day 4, including participants with persisting symptoms and complicated diverticulitis. This design excluded participants of interest for this review before randomisation. The study design introduced selection bias by undermining the concept of randomisation prior to intervention start and by selecting participants for randomisation. Therefore, this study was not considered a randomised controlled trial for this review and did not fulfil the inclusion criteria.

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