Outcome variation in the use and duration of antibiotic therapy in patients presenting with acute diverticulitis

Background: Optimal antibiotic duration for diverticulitis managed without procedural source control is unknown. While antibiotic-sparing approaches in select patients are supported by high quality data, up to 24% experience treatment failure. Here we assess outcomes stratified by antibiotic duration in diverticulitis patients treated on an outpatient basis after an emergency department (ED) visit. Methods: Employing the MarketScan^® database (2016–2022), adult patients with a diverticulitis-associated ED visit treated on an outpatient basis were identified. Claims for diverticulitis-directed antibiotics filled within three days of ED visit were captured. Antibiotic receipt/duration were compared for 90-day outcomes, including repeat diverticulitis-related ED visit, additional antibiotic prescriptions, and surgery. Outcomes were assessed using chi square, unadjusted and multivariable logistic regression. Results: Seventy-three thousand eight hundred ten patients were included; 54.6% were female, median age was 52 years. 11,311 (15.3%) patients did not fill an antibiotic prescription. Of those who filled one, median duration of prescription was 10.0 days. In unadjusted analysis, those who did not fill a prescription had comparable rates of surgery, but lower rates of subsequent antibiotic use (24.2% vs. 29.9%, p < 0.001) and repeat diverticulitis-related ED visits (4.9% vs. 6.0%, p < 0.001) than those with prescriptions. In an adjusted model these findings were recapitulated. Unadjusted comparisons of antibiotic duration revealed significant differences between groups. In adjusted models, durations longer than 10 days had higher odds of surgery than did shorter durations (OR = 2.20 for 11 + days vs. 7 days of duration [95% CI 1.72–2.66]). Conclusions: We report comparable or improved outcomes in an antibiotic-sparing approach to diverticulitis. Further, longer treatment durations were not associated with reduction in recurrent disease, and were associated with higher odds of eventual surgery. These data support institutional consideration for antibiotic-sparing protocols for appropriately selected patients with diverticulitis.