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Validation of the American Association for the Surgery of Trauma (AAST) Anatomic Severity Grading System for Acute Cholecystitis.
*BS Vera, *Kevin Y Pei, Kevin M. Schuster, Kimberly A. Davis
Yale School of Medicine, New Haven, CT

Objective: 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. This study validates the AAST anatomic grading system for acute cholecystitis.
Design: Retrospective cohort study. Grade I is acute cholecystitis, Grade II is gangrenous or emphysematous cholecystitis, Grade III is localized perforation, Grade IV and V have regional and systemic peritonitis.
Setting: Tertiary, academic, referral medical center
Patients: 315 patients admitted for acute cholecystitis between 2013 and 2016.
Interventions: None
Main Outcome Measures: Concordance between the AAST grade and outcome including mortality, length of stay (LOS), ICU use, and adverse events.
Results: There was very good interrater (2 independent raters) reliability for anatomic grading, κ=1.00, p<0.005. Incidence of complications, LOS, ICU use, and any adverse event increased with increasing anatomic grade (Table). When compared to Grade 1 disease, patients with Grade 2 were more likely to undergo cholecystectomy (OR 4.07 [ 1.93-8.56]), require ICU use (OR 2.41 [1.31 4.44]) and develop a complication (OR 2.07 [1.22 3.53]). Grade 3 patients were at higher risk of adverse events (OR 3.83 [1.34-10.94]) and ICU use (OR 8.07 [2.43-26.80]).
Conclusions: AAST severity scores were independently associated with clinical outcomes in patients with acute cholecystitis. Despite low grade disease (majority patients were Grade 1 & 2), complications were common, therefore a refinement of the scoring system may be necessary for more granular prediction.

GradenMean age (sd)FemaleMortalityAny ComplicationLOS (IQR)ICU use
I219 (69.5%)59.1 (19.5)54.8%12 (5.5%)70 (31.9%)3 (1-5)15.5%
II75 (23.8%)66.6 (16.8)56.0%7 (9.3%)37 (49.3%)*4 (2-7)30.7%*
III18 (5.7%)70.2 (11.5)55.6%3 (16.7%)12 (66.7%)*6.5 (5-8)*66.7%*
V3 (1.0%)61.3 (8.1)33.3%2 (66.7%)*2 (66.7%)11 (2-12)66.7%
*p<0.05 when compared to Grade I disease


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