Retrospective Analysis of Postoperative Antibiotics in Operative Complicated Appendicitis

Author(s):
Patrick McGillen; F. Thurston Drake; Andrew Vallejo; Tejal Brahmbhatt; Sabrina Sanchez

Background:

There is no consensus regarding the ideal postoperative antibiotic regimen for cases of surgically-managed acute complicated appendicitis. The purpose of this study was to investigate the different antibiotic regimens used for this purpose at our institution and their association with postoperative outcomes.

Hypothesis:

We hypothesized that neither route nor duration of antibiotic therapy would be associated with the development of surgical site infection (SSI) in this population.

Methods:

1,102 patients underwent appendectomy from 2012 to 2016. Of these, we performed an extensive chart review on the 146 diagnosed with complicated appendicitis based on standardized definitions. Descriptive and inferential statistics were used to evaluate the demographic and clinical characteristics of these patients, including postoperative antibiotic use and postoperative complications.

Results:

Of the 146 cases of complicated appendicitis identified, 120 (82.2%) were classified as perforated by the operative surgeon. These patients were significantly more likely to be started on antibiotics post-appendectomy (88.3% vs 34.6%, p <0.001) and have a longer length of stay (LOS) (p=0.009). Patients with and without perforation otherwise did not differ with regards to age, sex, comorbidities, presenting WBC, or ASA classification.

The development of a postoperative SSI was significantly associated with the presence of free fluid on preoperative imaging, a decision by the surgeon to leave a drain, and a longer LOS (p=0.007, p=0.006 and p<0.001, respectively). The duration of antibiotic treatment pre-SSI was significantly longer in patients who developed a SSI compared to those who did not (p=0.042).

On multiple logistic regression, patients receiving 2 days of antibiotics versus 1 day or 3+ days had similar odds of developing a SSI as patients that did not receive postoperative antibiotics. Route of antibiotic administration did not significantly affect the odds of developing an SSI. Both multivariate models were adjusted for free fluid on imaging, decision to leave a drain, and surgeon-defined perforation.

Conclusions:

In this cohort, operative surgeons successfully identified patients with complicated appendicitis who did not require postoperative antibiotics as a means to avert development of a SSI. For patients deemed to require antibiotics, 2 days of treatment were associated with reduced odds of SSI compared to shorter or longer antibiotic courses. These findings suggest that a prospective trial could clarify the optimal duration and route of antibiotic therapy in the setting of operative complicated appendicitis.