Validation of a new American Association for the Surgery of Trauma (AAST) anatomic severity grading system for acute cholecystitis.

Abstract

The American Association for the Surgery of Trauma (AAST) established anatomic grading to facilitate risk stratification and risk-adjusted outcomes in emergency general surgery. Cholecystitis severity was graded based on clinical, imaging, operative, and pathologic criteria. We aimed to validate the AAST anatomic grading system for acute cholecystitis. This is a retrospective cohort study including consecutive patients admitted with acute cholecystitis at an urban, tertiary medical center between 2013 and 2016. Grade 1 is acute cholecystitis, Grade 2 is gangrenous or emphysematous cholecystitis, Grade 3 is localized perforation, and Grades 4 and 5 have regional and systemic peritonitis, respectively. Concordance between the AAST grade and outcome including mortality, length of stay (LOS), ICU use, readmission, and complications were assessed using logistic regression. A total of 315 patients were included. There was very good inter-rater (two independent raters) reliability for anatomic grading, κ = 1.00, p < 0.005. The majority of patients were Grade 1 or Grade 2 (94%). Incidence of complications, LOS, ICU use, and any adverse event increased with increasing anatomic grade. When compared to Grade 1 disease, patients with Grade 2 were more likely to undergo cholecystectomy (OR 4.07 [1.93-8.56]). Grade 3 patients were at higher risk of adverse events (OR 3.83 [1.34-10.94]), longer LOS (OR 1.73 [1.03-2.92]), and ICU use (OR 8.07 [2.43-26.80]). AAST severity scores were independently associated with clinical outcomes in patients with acute cholecystitis. Despite low-grade disease, complications were common, and therefore a refinement of the scoring system may be necessary for more granular prediction. Epidemiologic/prognostic, level III.