Supplementary Material for: Systematic Review and Meta-Analysis of Postoperative Antibiotics for Patients with a Complex Appendicitis

Postoperative antibiotics are recommended after appendectomy for complex appendicitis to reduce infectious complications. The duration of this treatment varies considerably between and even within institutions. The aim of this review was to critically appraise studies on duration of antibiotic treatment following appendectomy for complex appendicitis. A systematic literature search according to the PRISMA guidelines was performed. Comparative studies evaluating different durations of postoperative antibiotic therapy. Primary endpoint was intra-abdominal abscess (IAA) after appendectomy. Secondary endpoints were surgical site infection, readmission and length of hospital stay. The quality of evidence was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool. Pooled event rates were calculated using a random-effects model. Nine studies reporting 2006 patients with complex appendicitis were included. The methodological quality of the included articles was poor. IAA was seen in 138 patients (8,6%). Meta-analysis revealed a statistically significant difference in IAA incidence between antibiotic treatment of ≤5 vs. >5 days (risk ratio (OR) 0.36 [95% CI 0.23–0.57] (p < 0.0001)) but not between ≤3 vs. >3 days (OR 0.81 [95% CI 0.38–1.74] (p = 0.59)). Descriptive statistics were used for secondary endpoints. The duration of postoperative antibiotic treatment is not associated with IAA following appendectomy for complex appendicitis.