Prophylactic Drainage after Appendectomy for Perforated Appendicitis in Adults: A Post Hoc Analysis of an EAST Multi-Center Study

Background: We sought to assess the efficacy of prophylactic abdominal drainage to prevent complications after appendectomy for perforated appendicitis. Methods: In this post hoc analysis of a prospective multi-center study of appendicitis in adults (≥ 18 years), we included patients with perforated appendicitis diagnosed intra-operatively. The 634 subjects were divided into groups on the basis of receipt of prophylactic drains. The demographics and outcomes analyzed were surgical site infection (SSI), intra-abdominal abscess (IAA), Clavien-Dindo complications, secondary interventions, and hospital length of stay (LOS). Multivariable logistic regression for the cumulative 30-day incidence of IAA was performed controlling for age, Charlson Comorbidity Index (CCI), antibiotic duration, presence of drains, and Operative American Association for the Surgery of Trauma (AAST) Grade. Results: In comparing the Drain (n = 159) versus No-Drain (n = 475) groups, there was no difference in the frequency of male gender (61% versus 55%; p = 0.168), weight (87.9 ± 27.9 versus 83.8 ± 23.4 kg; p = 0.071), Alvarado score (7 [6-8] versus 7 [6-8]; p = 0.591), white blood cell (WBC) count (14.8 ± 4.8 versus 14.9 ± 4.5; p = 0.867), or CCI (1 [0-3] versus 1 [0-2]; p = 0.113). The Drain group was significantly older (51 ± 16 versus 48 ± 17 years; p = 0.017). Drain use increased as AAST EGS Appendicitis Operative Severity Grade increased: Grade 3 (62/311; 20%), Grade 4 (46/168; 27%), and Grade 5 (51/155; 33%); p = 0.007. For index hospitalization, the Drain group had a higher complication rate (43% versus 28%; p = 0.001) and longer LOS (4 [3-7] versus 3 [1-5] days; p < 0.001). We could not detect a difference between the groups in the incidence of SSI, IAA, or secondary interventions. There was no difference in 30-day emergency department visits, re-admissions, or secondary interventions. Multi-variable logistic regression showed that only AAST Grade (odds ratio 2.7; 95% confidence interval7 1.5-4.7; p = 0.001) was predictive of the cumulative 30-day incidence of IAA. Conclusions: Prophylactic drainage after appendectomy for perforated appendicitis in adults is not associated with fewer intra-abdominal abscesses but is associated with longer hospital LOS. Increasing AAST EGS Appendicitis Operative Grade is a strong predictor of intra-abdominal abscess.