Comparison of American Association for the Surgery of Trauma grading scale with modified Hinchey classification in acute colonic diverticulitis: A pilot study

BACKGROUND The American Association for the Surgery of Trauma (AAST) developed a severity scale for surgical conditions, including diverticulitis. The Hinchey classification requires operative intervention yet remains the established scoring system for acute diverticulitis. This is a pilot study to compare the AAST grading scale for acute colonic diverticulitis with the traditional Hinchey classification. We hypothesize that the AAST classification scale is equivalent to the Hinchey in predicting outcomes. METHODS This is a retrospective cohort study at an academic medical center. A consecutive sample of patients with acute diverticulitis and computed tomography imaging was reviewed. Chart review identified demographic and physiologic data with interventional and clinical outcomes. Each computed tomography scan was assigned AAST and modified Hinchey classification scores by a radiologist. Multivariate regression and receiver operating characteristic curve analysis compared six outcomes: need for procedure, complication, intensive care unit (ICU) admission, length of stay, 30-day readmission, and mortality. RESULTS One hundred twenty-nine patients were included. Of the total patients, 42.6% required procedural intervention, 21.7% required ICU admission, 18.6% were readmitted, and 6.2% died. Both AAST and Hinchey predicted the need for operation (AAST odds ratios, 1.55, 12.7, 18.09, and 77.24 for stages 2-5; Hinchey odds ratios, 8.85, 11.49, and 22.9 for stages 1b-3, stage 4 predicted perfectly). The need for operation c-statistics (area under the curve) for AAST and Hinchey was 0.80 and 0.83 for Hinchey and AAST, respectively (p= 0.35). The complication c-statistics curve for AAST and Hinchey was 0.83 and 0.80, respectively (p= 0.33). The AAST and Hinchey scores were less predictive for ICU admission, readmission, and mortality with c-statistics of less than 0.80. CONCLUSION The AAST grading of acute diverticulitis is equivalent to the modified Hinchey classification in predicting procedural intervention and complications. The AAST system may be preferable to Hinchey because it can be applied preoperatively. Although this pilot study demonstrated that the AAST score predicts surgical need, a larger study is required to evaluate the AAST score for other outcomes.