Composite Criteria for Non-Operative Management of Acute Non-Complicated Appendicitis Result in Low Failure Rates

Background: The aim of this study is to investigate the outcomes of conservative management of non-complicated acute appendicitis (AA) using our unique institutional protocol, and to compare between these and the outcomes of operative management. Methods: Patients admitted to our institution between March 2016 and October 2019 with non-complicated AA were grouped according to their initial management: non-operative versus surgical. Our unique protocol for non-operative management includes: pain < 3 days; afebrile upon admission; non-gravid; WBC <15,000 (× 10⁹/L); CRP < 5 mg/dl; appendix diameter < 1 cm; no appendicolith on imaging; no prior episode of AA; no history of Inflammatory Bowel Disease; no evidence of peritonitis on physical examination. The primary outcome measured was failure of non-surgical management during the index admission. Secondary outcomes included recurrence rate, readmissions, complications, length of antibiotic treatment and length of stay (LOS). Results: A total of 695 patients were included, 436 in the operative group and 259 in the non-surgical treatment group. The mean follow-up time was 1004.9 ± 205.7 days. Patients initially treated conservatively rarely required surgery during their index admission (6.9%). Recurrence rate was 19.1% after a mean follow up of 33.4 months. The overall failure rate of conservative management was documented in 20.8% of the patients. The complication rate was higher in those treated with upfront surgery (1.6% vs. 0.4%, p < 0.001). The overall LOS was not statistically different between the groups. Conclusions: Our composite protocol for non-surgical management of non-complicated AA results in a low failure rate. A well calculated patient treatment allocation in non-complicated AA can advocate for wide-spread use of the conservative approach.