Graded operative autonomy in emergency appendectomy mirrors case-complexity: surgical training insights from the SnapAppy prospective observational study

Introduction: Surgical skill, a summation of acquired wisdom, deliberate practice and experience, has been linked to improved patient outcomes. Graded mentored exposure to pathologies and operative techniques is a cornerstone of surgical training. Appendectomy is one of the first procedures surgical trainees perform independently. We hypothesize that, given the embedded training ethos in surgery, coupled with the steep learning curve required to achieve trainer-recognition of independent competency, 'real-world' clinical outcomes following appendectomy for the treatment of acute appendicitis are operator agnostic. The principle of graded autonomy matches trainees with clinical conditions that they can manage independently, and increased complexity drives attending input or assumption of the technical aspects of care, and therefore, one cannot detect an impact of operator experience on outcomes. Materials and methods: This study is a subgroup analysis of the SnapAppy international time-bound prospective observational cohort study (ClinicalTrials.gov Trial #NCT04365491), including all consecutive patients aged ≥ 15 who underwent appendectomy for appendicitis during a three-month period in 2020-2021. Patient- and surgeon-specific variables, as well as 90-day postoperative outcomes, were collected. Patients were grouped based on operating surgeon experience (trainee only, trainee with direct attending supervision, attending only). Poisson and quantile regression models were used to (adjusted for patient-associated confounders) assess the relationship between surgical experience and postoperative complications or hospital length of stay (hLOS), respectively, adjusted for patient-associated confounders. The primary outcome of interest was any complications within 90 days. Results: A total of 4,347 patients from 71 centers in 14 countries were included. Patients operated on by trainees were younger (Median (IQR) 33 [24-46] vs 38 [26-55] years, p < 0.001), had lower ASA classifications (ASA ≥ 3: 6.6% vs 11.6%, p < 0.001) and fewer comorbidities compared to those operated on by attendings. Additionally, trainees operated alone on fewer patients with appendiceal perforation (AAST severity grade ≥ 3: 8.7% vs 15.6%, p < 0.001). Regression analyses revealed no association between operator experience and complications (IRR 1.03 95%CI 0.83-1.28 for trainee vs attending; IRR 1.13 95%CI 0.89-1.42 for supervised trainee vs attending) or hLOS. Conclusion: The linkage of case complexity with operator experience within the context of graduated autonomy is a central tenet of surgical training. Either subconsciously, or by design, patients operated on by trainees were younger, fitter and with earlier stage disease. At least in part, these explain why clinical outcomes following appendectomy do not differ depending on the experience of the operating surgeon.