Validation of the American Association for the Surgery of Trauma's emergency general surgery breast infection grading system

Background: The American Association for the Surgery of Trauma (AAST) developed emergency general surgery (EGS) grading systems for multiple diseases to standardize classification of disease severity. The grading system for breast infections has not been validated. We aimed to validate the AAST breast infection grading system. Methods: Multi-institutional retrospective review of all adult patients with a breast infection diagnosis at Mayo Clinic Rochester 1/2015-10/2015 and Pietermaritzburg South African Hospital 1/2010-4/2016 was performed. AAST EGS grades were assigned by two independent reviewers. Inter-rater reliability was measured using the agreement statistic (kappa). Final AAST grade was correlated with patient and treatment factors using Pearson's correlation coefficient. Results: Two hundred twenty-five patients were identified: grade I (n = 152, 67.6%), II (n = 44, 19.6%), III (n = 25, 11.1%), IV (n = 0, 0.0%), and V (n = 4, 1.8%). At Mayo Clinic Rochester, AAST grades ranged from I-III. The kappa was 1.0, demonstrating 100% agreement between reviewers. Within the South African patients, grades included II, III, and V, with a kappa of 0.34, due to issues of the grading system application to this patient population. Treatment received correlated with AAST grade; less severe breast infections (grade I-II) received more oral antibiotics (correlation [−0.23, P = 0.0004]), however, higher AAST grades (III) received more intravenous antibiotics (correlation 0.29, P <0.0001). Conclusions: The AAST EGS breast infection grading system demonstrates reliability and ease for disease classification, and correlates with required treatment, in patients presenting with low-to-moderate severity infections at an academic medical center; however, it needs further refinement before being applicable to patients with more severe disease presenting for treatment in low-/middle-income countries.