1. Treatment of outpatient diverticulitis with amoxicillin-clavulanate was shown to be comparably effective as a treatment of metronidazole-with-fluoroquinolone for outpatient diverticulitis.
2. The 1-year risk for Clostridium Difficile infection (CDI) was significantly higher for metronidazole-with-fluoroquinolone compared to amoxicillin-clavulanate.
Evidence Rating Level: 2 (Good)
Study Rundown: Acute outpatient diverticulitis is an inflammatory condition of the colon, and is often treated with antibiotics. The two most commonly prescribed regimens are metronidazole-with-fluoroquinolone and amoxicillin-clavulanate. However, there is a gap in knowledge as to comparing the effectiveness and harms of the two treatments. As such, this study compared the effectiveness of metronidazole-with-fluoroquinolone and amoxicillin-clavulanate in patients with outpatient diverticulitis. This study found that there was no difference between the two treatment groups regarding risks for diverticulitis admissions, visits to the emergency department (ED) or outpatient clinics, urgent surgery, and elective surgery. However, there was a higher one-year risk for CDI in the metronidazole-with-fluoroquinolone group compared to the amoxicillin-clavulanate group. This study was limited by analyzing claims data, which only reflect dispensing of prescription antibiotics and not their use or consumption. Nonetheless, these study’s findings are significant, as they demonstrate that metronidazole-with-fluoroquinolone and amoxicillin-clavulanate have comparable effectiveness, despite metronidazole-with-fluoroquinolone being associated with a higher risk for CDI.
In-Depth [retrospective cohort]: This retrospective cohort study examined 2 nationwide cohorts, MarketScan and Medicare. In the MarketScan cohort, there were 106,363 patients who received metronidazole-with-fluoroquinolone and 13,160 patients who received amoxicillin-clavulanate. In the Medicare cohort, there were 17,639 patients who received metronidazole-with-fluoroquinolone and 2,709 patients who received amoxicillin-clavulanate in the Medicare cohort. Patients who had continuous insurance and no previous diverticulitis-related care were included in the study. Patients who were immunocompromised or immunosuppressed were excluded from the study. The primary outcomes measured inpatient admission for diverticulitis, urgent surgery, and CDI in the year after diagnosis. Among the two groups, in the MarketScan cohort, there were no differences between treatment groups in diverticulitis specific 1-year hospital admission (risk difference [RD], 0.1 percentage points; 95% confidence interval [CI], -0.3 to 0.6), 1-year urgent surgery risk (RD, 0.0 percentage points; 95% CI, -0.1 to 0.1), or 3-year elective surgery risk (RD, 0.2 percentage points; 95% CI, -0.3 to 0.7), and similar 1-year risk for CDI of 0.3% (RD, 0.0 percentage points; 95% CI, -0.1 to 0.1). In the Medicare cohort, there were also no differences between treatment groups in diverticulitis-specific 1-year hospital admission (RD, 0.1 percentage points; 95% CI, -0.7 to 0.9) or 3-year elective surgery risk (RD, -0.3 percentage points; 95% CI, -1.1 to 0.4). However, the 1-year risk for CDI was significantly higher for metronidazole-with-fluoroquinolone (1.2%) compared to amoxicillin-clavulanate (0.6%) (RD, 0.6 percentage points; 95% CI, 0.2 to 1.0). Overall, this study determined the comparable effectiveness of both antibiotic regimens in treating outpatient diverticulitis, but prescribing amoxicillin-clavulanate instead of metronidazole-with-fluoroquinolone may provide a lower risk for developing CDI.
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