Predictors of appendicectomy one year after antibiotic treatment for acute appendicitis: Insights from a prospective, multicentre, observational study.

Background: Surgeons are sometimes reluctant to manage uncomplicated appendicitis non-operatively. Reasons cited include the risk of recurrent appendicitis and the risk of missed appendiceal malignancy. The aim of this study was to address these uncertainties and determine the long-term efficacy of antibiotic versus operative management of appendicitis.

Method: One-year follow-up of patients enrolled in the multicentre, COVID:HAREM cohort study during March-June 2020 was performed. Initial operative or non-operative management was determined on a case-by-case basis by the responsible surgeon. Outcomes were appendicectomy rate at 1-year, histology of removed appendix and predictors of unsuccessful antibiotic treatment.

Results: A total of 625 patients who had non-operative management were included. Emergency appendicectomy had been performed by 1-year in 24% (149/625), with a median time to appendicectomy of 12 days [IQR 1-77] from presentation. Thirty-one patients had elective appendicectomy. Normal histology was reported in 6% of emergency procedures and 58% of elective ones. There were 7 malignancies and 3 neuroendocrine tumors identified at histology. All patients with malignant histology had ≥1 risk factors for malignancy at initial presentation. Faecolithiasis (hazard ratios (HR) 2.3, 95% confidence intervals (CI) 1.51-3.49) and a high Adult Appendicitis Score (AAS >16; HR 2.44, 95% CI 1.52-3.92) were independent risk factors for unsuccessful non-operative management.

Conclusion: At 1 year, 71% of patients managed non-operatively did not undergo an appendicectomy. Recurrence of appendicitis was associated with faecolithiasis and a high AAS. Patients at higher risk for appendiceal malignancy should have targeted follow-up. These factors should be considered when counseling patients on non-operative management.