K. K. Somers1, D. C. Eastwood2, Y. Liu2, M. J. Arca1 1Medical College Of Wisconsin,Children’s Hospital Of Wisconsin And Division Of Pediatric Surgery/Department Of Surgery,Milwaukee, WI, USA 2Medical College Of Wisconsin,Division Of Biostatistics/ Inbstitute Of Health And Equity,Milwaukee, WI, USA
Introduction: Antibiotics are an integral part of treatment of both acute and complicated appendicitis. We sought to determine if an association exists between surgical site infections (SSI) in patients with acute and complicated appendicitis and the timing of perioperative antibiotics.
Methods: We performed single institution review utilizing a prospectively collected appendicitis database on all patients with acute (n=988) and complex appendicitis (n=561) from January 1, 2013 until December 31, 2017. Duration of intravenous antibiotics in complicated appendicitis was determined by clinical criteria (afebrile, non-tachycardia, and able to tolerate feeding). The primary outcome measure is development of surgical site infection (SSI) within 60 days of surgery.
Results: For acute appendicitis (AA), SSI occurred in 2.5% of patients with no statistical significance (p=0.566) seen between those who received preoperative antibiotics within 60 minutes of incision (2.1%) versus greater than 60 minutes (3%). Patients who received post-operative antibiotics had 2.65% SSI compared to 1.4% of patients who did not receive post-operative antibiotics (p=0.718). For complicated appendicitis (CA), SSI occurred in 19.1% of patients with no statistical significance (p=0.739) between those who received preoperative antibiotics within 60 minutes of incision (19.6%) versus greater than 60 minutes (18.5%). A grid search for the optimal window of preoperative antibiotic yielded the time interval <20 minutes or >80 minutes prior to incision to have less SSI. Adjusting for age, patients given antibiotic in the 20-80 window had significantly fewer complications after discharge (OR=0.41, 95% CI 0.20, 0.84, p=0.0157). Two CA groupings emerged with respect to clinical response: (1) Early Responders (ER), who met discharge criteria in 6 days or less, and (2) Late Responders (LR) who met discharge criteria >6 days. ER’s SSI rates (8.8%) were statistically lower (49.3%, p<0.001) and had less need for readmission compared to LR (4.0% versus 18.3%, p<0.001). ER required a significantly shorter duration of IV antibiotics and length of stay as well as a much lower rate of postoperative infection and need for readmission compared to LR. In the ER group, we noted a higher rate of SSI in patients who received 1 (25%) or 2 (14%) days of IV compared to 3-6 days (average 8%). In logistic regression controlling for age at surgery, ER patients with oral antibiotics had lower odds of complication than patients discharged with no oral antibiotics (OR 0.41, 95% CI 0.19, 0.89; p=0.0233). In contrast, oral antibiotics did not protect patients in the LR group from having post-operative SSI.
Conclusion: Preoperative antibiotics given within 60 minutes of incision did not confer an advantage against SSI in AA or CA. In AA, postoperative antibiotics did not protect against SSI. In CA, physiologic response to treatment should guide therapy.