In mild acute diverticulitis, outpatient therapy without antibiotics was noninferior to antibiotics

The DINAMO-study, a randomized controlled noninferiority trial conducted at 15 hospitals in Spain, included 480 patients seen in the ED with symptoms compatible with acute diverticulitis, diagnosed by CT and judged to be mild. Patients were randomized to either usual treatment (875 mg of amoxicillin and 125 mg of clavulanic acid every eight hours along with anti-inflammatory and symptomatic treatment) or the experimental intervention of only anti-inflammatory and symptomatic treatment. The results showed that outpatient therapy without antibiotics (ATBs) was noninferior to therapy with ATBs for reducing hospital admission at 90 days.

The study was published in the November 2021 Annals of Surgery and was summarized in the November ACP Gastroenterology Monthly. The following commentary by Meera Jain, MD, FACP, and Amy Dechet, MD, was published in the ACP Journal Club section of the February Annals of Internal Medicine.

The AVOD and DIABOLO randomized controlled trials, neither of which had a placebo or blinding, showed that observation without ATBs has no worse outcomes at ≤11 years in inpatients with a first episode of uncomplicated acute diverticulitis. If diverticulitis is more of an inflammatory than an infectious process, it makes sense that withholding ATBs does not adversely affect outcomes. The DINAMO-study by Mora-López and colleagues is the first outpatient trial to show that withholding ATBs may not have inferior outcomes.

Curiously, both groups in the DINAMO-study were given nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and omeprazole, none of which is recommended in diverticulitis guidelines. Rather than the absence of ATBs, perhaps the trial's results are partly explained by use of NSAIDs and/or acetaminophen in both groups and their actions on an inflammatory process and subsequent reduction in pain and/or fever.

The strict inclusion and exclusion criteria of the trial required attention to clinical, laboratory, and CT scan features and a monitoring period in the ED before discharge, which may be difficult to achieve in busy outpatient clinics.

Nonetheless, one could extrapolate beyond the inpatient studies and DINAMO-study to healthy patients with mild symptoms initially evaluated in an outpatient setting where disease prevalence and overall risks are likely lower than in ED or inpatient settings, and forgo ATBs with close follow-up.

ATB stewardship is essential for preventing multidrug resistant organisms, Clostridioides difficile colitis, and other drug adverse events, and for protecting the gut microbiome. The DINAMO-study adds data from an outpatient setting, suggests we may be able to forgo ATBs in healthy patients with mild acute diverticulitis, and supports the 2020 European Society of Coloproctology recommendations not to use ATBs routinely in uncomplicated acute diverticulitis. Whether NSAIDS and/or acetaminophen had a role in this trial's outcome requires further investigation.