Evaluating the association between American Association for the Surgery of Trauma emergency general surgery anatomic severity grades and clinical outcomes using national claims data

BACKGROUND: Emergency general surgery (EGS) encompasses a heterogeneous population of acutely ill patients, and standardized methods for determining disease severity are essential for comparative effectiveness research and quality improvement initiatives. The American Association for the Surgery of Trauma (AAST) has developed a grading system for the anatomic severity of 16 EGS conditions; however, little is known regarding how well these AAST EGS grades can be approximated by diagnosis codes in administrative databases. METHODS: We identified adults admitted for 16 common EGS conditions in the 2012 to 2017q3 National Inpatient Sample. Disease severity strata were assigned using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes based on AAST EGS anatomic severity grades. We evaluated whether assigned EGS severity (multiple strata or dichotomized into less versus more complex) were associated with in-hospital mortality, complications, length of stay, discharge disposition, and costs. Analyses were adjusted for age, sex, comorbidities, hospital traits, geography, and year. RESULTS: We identified 10,886,822 EGS admissions. The number of anatomic severity strata derived from ICD-9/10-CM codes varied by EGS condition and by year. Four conditions mapped to four strata across all years. Two conditions mapped to four strata with ICD-9-CM codes but only two or three strata with ICD-10-CM codes. Others mapped to three or fewer strata. When dichotomized into less versus more complex disease, patients with more complex disease had worse outcomes across all 16 conditions. The addition of multiple strata beyond a binary measure of complex disease, however, showed inconsistent results. CONCLUSION: Classification of common EGS conditions according to anatomic severity is feasible with International Classification of Diseases codes. No condition mapped to five distinct severity grades, and the relationship between increasing grade and outcomes was not consistent across conditions. However, a standardized measure of severity, even if just dichotomized into less versus more complex, can inform ongoing efforts aimed at optimizing outcomes for EGS patients across the nation. LEVEL OF EVIDENCE: Prognostic, level III.