Outpatient treatment with amoxicillin-clavulanate is safe and effective and may reduce risk for fluoroquinolone-related harms, according to a recent study.
Researchers used data from two nationwide U.S. claims databases, one from 2000 to 2018 including patients ages 18 to 64 years with private employer-sponsored insurance and one from 2006 to 2015 including patients ages 65 years or older with Medicare, to compare the effectiveness of combination treatment with metronidazole-fluoroquinolone and amoxicillin-clavulanate for a first occurrence of outpatient diverticulitis. The primary outcome measures were one-year risks for inpatient admission, urgent surgery, and Clostridioides difficile infection (CDI) and three-year risk for elective surgery. The results were published Feb. 23 by Annals of Internal Medicine.
The first database of younger patients included 106,361 (89.0%) new users of metronidazole-fluoroquinolone and 13,160 (11.0%) new users of amoxicillin-clavulanate. The median patient age was 52 years, and 47% were women. No between-group differences were seen in one-year admission risk (risk difference, 0.1 percentage point [95% CI, −0.3 to 0.6 percentage point]), one-year urgent surgery risk (risk difference, 0.0 percentage points [95% CI, −0.1 to 0.1 percentage point]), three-year elective surgery risk (risk difference, 0.2 percentage point [95% CI, −0.3 to 0.7 percentage point]), or one-year CDI risk (risk difference, 0.0 percentage points [95% CI, −0.1 to 0.1 percentage point]).
The second database of Medicare patients included 17,639 (86.7%) new users of metronidazole-fluoroquinolone and 2,709 (13.3%) new users of amoxicillin-clavulanate. The median patient age was 73 years, and 67.9% were women. In this database, no between-group differences were seen for one-year admission risk, one-year urgent surgery risk, or three-year elective surgery risk (risk differences, 0.1 percentage point [95% CI, −0.7 to 0.9 percentage point], −0.2 percentage point [95% CI, −0.6 to 0.1], and −0.3 percentage point [95% CI, −1.1 to 0.4], respectively). One-year risk for CDI infection was higher in those receiving metronidazole-fluoroquinolone than in those receiving amoxicillin-clavulanate (risk difference, 0.6 percentage point [95% CI, 0.2 to 1.0 percentage point]).
The authors noted that their data were based on dispensed antibiotics reimbursed by insurance rather than antibiotic use and that they did not examine all safety outcomes, including drug-induced liver injury, among other limitations. They concluded that amoxicillin-clavulanate is as effective as metronidazole-fluoroquinolone for treatment of outpatient diverticulitis, with negligible between-group differences in risk for diverticulitis admissions, ED or outpatient visits, urgent surgery, and elective surgery. “When selectively treating outpatient diverticulitis with antibiotics, physicians may consider treatment with amoxicillin-clavulanate over metronidazole-with-fluoroquinolone to reduce the risk for serious harms associated with fluoroquinolone use, including CDI,” the authors wrote.