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.