Higher Rates of New Colon Neoplasm in Interval vs. Primary Appendectomies-A Coarsened Exact Matching Analysis.

Background and aims: While there is low risk of emergent appendectomy patients becoming diagnosed with a neoplasm, the rates are much higher in patients undergoing interval appendectomies. This study compares the incidence rates of new primary right colon neoplasms and postoperative complications between interval and primary appendectomies.

Methods: We performed a retrospective cohort study from 2001 to 2020 involving patients from 92 healthcare organizations within TriNetX. Patients' diagnosis and procedure were extracted from ICD and CPT codes. Primary and interval appendectomy (IA) cohorts were defined as having an appendectomy procedure 0-14 and 15-90 days from the initial diagnosis, respectively. Patients in each cohort were matched 1:1 on demographics via Coarsened Exact Matching (CEM). Postoperative complications and oncological outcomes were defined by specific ICD and/or CPT codes.

Results: Post-matching, there were 2803 patients included in each cohort. IA patients were associated with 3.07 times greater incidence rates of malignant neoplasm of the right colon and appendix (p < 0.001). However, IA patients were associated with 2.63 times lower postoperative complication rates (p < 0.001).

Conclusion: IA patients are more likely to be diagnosed with new right-sided neoplasms postoperatively. Future studies are necessary to determine appropriate cancer screening methods for IA candidates.