Discordance in Appendicitis Grading and the Association with Outcomes: A Post-Hoc Analysis of an EAST Multicenter Study

Background: The American Association for the Surgery of Trauma (AAST) appendicitis severity grading criteria use independent subscales for radiologists (Rad), surgeons (Surg), and pathologists (Path). We reviewed the EAST Multicenter Study of the Treatment of Appendicitis in America: Acute, Perforated, and Gangrenous (MUSTANG) database to determine rates of discordance and clinical consequences of inaccuracy. Materials and Methods: A confusion matrix was constructed for pairs among Rad, Surg, and Path. Accuracy was reported using chronologically latest diagnosis as gold standard. “Concordance” (C) was achieved when both agreed on the severity grade and “Discordance”(D) when they disagreed. A composite endpoint(“COMP”= 30-d incidence of surgical site infection, abscess, wound complication, Clavien-Dindo complication, secondary intervention, ED[Emergency Department] visit, hospital readmission, and mortality) was compared between C versus D groups via χ² test with Bonferroni correction to define statistical significance(P = 0.05/9 = 0.005). Results: For each pair and diagnosis, subjects were categorized as C or D and compared for the incidence of COMP. Incidence of COMP for Surg and/or Path in C versus D: 16% versus. 26% (p = 0.006, NS by Bonferroni) for acute (A), 39% versus 33% (p = 0.39) for gangrenous (G), and 48% versus 37% (p = 0.035, NS by Bonferroni) for perforated (P). For Rad and/or Path in C versus. D: 17% versus 42% (p < 0.001) for A, 27% versus 31% (p = 0.95) for G, and 56% versus 48% (p = 0.48) for P. For C versus D: 17% versus 40% (p < 0.001) for A, 36% versus 26% (p = 0.43) for G, and 51% versus 39% (p = 0.29) for P. Conclusions: In appendicitis treated by appendectomy, surgeons are most accurate at diagnosing acute appendicitis and least accurate at diagnosing gangrenous. Radiologists are less accurate for all categories. When the surgeon is wrong, clinical outcomes are not significantly worse. However, when the radiologist is wrong about acute appendicitis, patients have worse clinical outcomes.