COMPARISON OF AAST GRADING SCALE TO MODIFIED HINCHEY CLASSIFICATION IN ACUTE COLONIC DIVERTICULITIS: A PILOT STUDY

BACKGROUND: The 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 to 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 (CT) imaging was reviewed. Chart review identified demographic and physiologic data with interventional and clinical outcomes. Each CT scan was assigned AAST and modified Hinchey classification scores by a radiologist. Multivariate regression and receiver-operative curve (ROC) analysis compared 6 outcomes: need for procedure, complication, ICU admission, length of stay, 30-day readmission, and mortality. RESULTS: 129 patients were included. 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 (OR) 1.55,12.7, 18.09, 77.24 for stage 2-5, Hinchey (OR) 8.85, 11.49, 22.9 for stage 1b-3, stage 4 predicted perfectly). The need for operation c-statistics (AUC) for AAST and Hinchey were 0.80 and 0.83 for Hinchey and AAST, respectively (p=0.35). The complication c-statistics curve for AAST and Hinchey were 0.83 and 0.80, respectively (p=0.33). AAST and Hinchey scores were less predictive for ICU admission, readmission, and mortality with c-statistics less than 0.80. DISCUSSION: 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 as 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. LEVEL OF EVIDENCE: Level III.Prognostic and Epidemiological study.