Study Flags Overuse of Antibiotics for Diverticulitis

Despite guidelines discouraging antibiotics in many uncomplicated diverticulitis cases, nearly everyone got one in a retrospective cohort study across Department of Veterans Affairs (VA) facilities.

Of more than 33,000 outpatient visits for uncomplicated diverticulitis during 2015 to 2025, clinicians prescribed antibiotics 96.6% of the time, with annual rates never falling below 95.6%, reported researchers led by Jesse Sutton, PharmD, of the Minneapolis VA Health Care System.

“Antibiotics were routinely prescribed for uncomplicated diverticulitis without meaningful change in the 10 years after guideline recommendations began calling for selective use,” Sutton and colleagues wrote in Annals of Internal Medicine. “Interventions are needed to align antibiotic prescribing with current guidelines to reduce harms of unnecessary antibiotic exposure.”

Uncomplicated diverticulitis is the most common form of the inflammatory colon condition, with only 12% of patients having complicated diverticulitis. While clinical trials, antibiotic stewardship campaigns, and clinical guidelines have moved away from supporting routine antibiotics prescriptions, prescribing rates have remained high, Sutton told MedPage Today.

“The default should probably not be to routinely do this every time,” Sutton said. “There’s far better evidence for no antibiotics in uncomplicated diverticulitis than there is for many other prescribing decisions people make on a daily basis.”

A 2020 clinical practice update by the American Gastroenterological Association noted that antibiotics “can be used selectively, rather than routinely, in immunocompetent patients with mild uncomplicated diverticulitis.” Antibiotics are recommended for uncomplicated diverticulitis in patients with comorbidities or who are frail, present with refractory symptoms or vomiting, have a C-reactive protein greater than 140 mg/L, or have a baseline white blood cell count greater than 15 per 10⁹ cells/L.

Those conditions, however, weren’t common among the 28,474 unique VA study patients, Sutton said. Most were healthy people without many of the systemic signs that guidelines suggest indicate a need for antibiotics.

The study included 33,634 emergency department (90%) or urgent care visits at 120 VA facilities by patients with a primary or secondary diagnosis of uncomplicated diverticulitis. Patients were excluded if they didn’t have an abdominal CT scan performed, were hospitalized within 24 hours after a visit, or had a diverticulitis diagnosis in the prior 90 days.

Median patient age was 63 years, and 90% were male. About three-fourths were white, one-fifth were Black, and 11% were Hispanic, and the median body mass index was 30.6. Over 20% of the patients were smokers, 2% had diabetes with complications, 3% had frailty or dementia, and the median Charlson Comorbidity Index score was 0.

“There weren’t that many comorbidities, which we were extremely surprised by,” Sutton observed.

The study’s primary outcome was an antibiotic ordered on the same or next day after a visit, with the type of antibiotic as the secondary outcome.

Fluoroquinolone-based regimens were prescribed most often (45.6%), followed by amoxicillin-clavulanate regimens (42.7%). The predominant regimen shifted over the decade, from fluoroquinolone-based in 2015 to amoxicillin-clavulanate by 2025.

Study limitations included the potential for misclassification of uncomplicated diverticulitis via inaccurate diagnosis codes and researchers’ reliance on electronic medical records to track antibiotic prescriptions.