The American Association for the Surgery of Trauma Emergency General Surgery Anatomic Severity Scoring System as a predictor of cost in appendicitis

Background: The World Society for Emergency Surgery determined that for appendicitis managed with appendectomy, there is a paucity of evidence evaluating costs with respect to disease severity. The American Association for the Surgery of Trauma (AAST) disease severity grading system is valid and generalizable for appendicitis. We aimed to evaluate hospitalization costs incurred by patients with increasing disease severity as defined by the AAST. We hypothesized that increasing disease severity would be associated with greater cost. Methods: Single-institution review of adults (≥ 18 years old) undergoing appendectomy for acute appendicitis during 2010–2016. Demographics, comorbidities, operative details, hospital stay, complications, and institutional cost data were collected. AAST grades were assigned by two independent reviewers based on operative findings. Total cost was ascertained from billing data and normalized to median grade I cost. Non-parametric linear regression was utilized to assess the association of several covariates and cost. Results: Evaluated patients (n = 1187) had a median [interquartile range] age of 37 [26–55] and 45% (n = 542) were female. There were 747 (63%) patients with Grade I disease, 219 (19%) with Grade II, 126 (11%) with Grade III, 50 (4%) with Grade IV, and 45 (4%) with Grade V. The median normalized cost of hospitalization was 1 [0.9–1.2]. Increasing AAST grade was associated with increasing cost (ρ = 0.39; p < 0.0001). Length of stay exhibited the strongest association with cost (ρ = 0.5; p < 0.0001), followed by AAST grade (ρ = 0.39), Clavien–Dindo Index (ρ = 0.37; p < 0.0001), age-adjusted Charlson score (ρ = 0.31; p < 0.0001), and surgical wound classification (ρ = 0.3; p < 0.0001). Conclusions: Increasing anatomic severity, as defined by AAST grade, is associated with increasing cost of hospitalization and clinical outcomes. The AAST grade compares favorably to other predictors of cost. Future analyses evaluating appendicitis reimbursement stand to benefit from utilization of the AAST grade.