Complicated Appendicitis: Are Extended Antibiotics Necessary? A Post Hoc Analysis of the EAST Appendicitis "MUSTANG" Study

Background: The need for extended postoperative antibiotics (Abx) for complicated (gangrenous or perforated) appendicitis (CA) remains unclear. We hypothesize that giving <= 24 h of Abx for CA is not inferior to a longer duration in preventing infectious complications after appendectomy. Methods: In this post hoc analysis of a prospective multicenter study, only patients with intraoperative diagnosis of CA were included. ANOVA and Chi-squared tests were used to compare length of stay, 30-day readmission rates, surgical site infection (SSI), and intra-abdominal abscess (IAA) between patients receiving >= 96 h and <= 24 h of Abx. Results: Of 751 patients with CA, 704 met inclusion criteria. Mean age was 48 (+/- 17) y; 391 (56%) were male. A total of 185 (26%) received Abx for <= 24 h and 100 (14% of overall) received no Abx. 85 (12%) patients were lost to follow-up at 30 d postop. Twenty-seven (4%) patients developed an SSI (<= 24 h = 5 (3%), >= 96 h = 22 (5%), P = 0.502) and 82 (13%) developed IAA (<= 24 h = 11 (7%), >= 96 h = 71 (15%), P = 0.008) within 30d postop. Sixty-six (11%) patients underwent a secondary intervention for infection within 30 d postop. 41% of SSIs (11/27) and 60% (49/82) of IAA occurred during the index hospitalization. On the multivariate analysis, there was not any evidence of an association between the duration of Abx and an increased rate of SSI (P = 0.539), IAA (P = 0.274), emergency department visits (P = 0.509), readmission (P = 0.911), or secondary interventions (P = 0.523). Conclusions: No evidence of an association between the duration of Abx (<= 24 h versus >= 96 h) for complicated appendicitis and an increased rate of SSI was observed and <= 24 h duration was associated with shorter length of stay. Because of possible selection bias, adequately powered randomized trials are required to definitely prove noninferiority of shorter course Abx duration. (C) 2019 Published by Elsevier Inc.