Multicenter validation of the American Association for the Surgery of Trauma grading scale for acute cholecystitis

Abstract

BACKGROUND The American Association for the Surgery of Trauma (AAST) patient assessment committee has created grading systems for emergency general surgery diseases to assist with clinical decision making and risk adjustment during research. Single-institution studies have validated the cholecystitis grading system as associated with patient outcomes. Our aim was to validate the grading system in a multi-institutional fashion and compare it with the Parkland grade and Tokyo Guidelines for acute cholecystitis. METHODS Patients presenting with acute cholecystitis to 1 of 8 institutions were enrolled. Discrete data to assign the AAST grade were collected. The Parkland grade was collected prospectively from the operative surgeon from four institutions. Parkland grade, Tokyo Guidelines, AAST grade, and the AAST preoperative grade (clinical and imaging subscales) were compared using linear and logistic regression to the need for surgical “bailout” (subtotal or fenestrated cholecystectomy, or cholecystostomy), conversion to open, surgical complications (bile leak, surgical site infection, bile duct injury), all complications, and operative time. RESULTS Of 861 patients, 781 underwent cholecystectomy. Mean (SD) age was 51.1 (18.6), and 62.7% were female. There were six deaths. Median AAST grade was 2 (interquartile range [IQR], 1–2), and median Parkland grade was 3 (interquartile range [IQR], 2–4). Median AAST clinical and imaging grades were 2 (IQR, 2–2) and 1 (IQR, 0–1), respectively. Higher grades were associated with longer operative times, and worse outcomes although few were significant. The Parkland grade outperformed the AAST grade based on area under the receiver operating characteristic curve. CONCLUSION The AAST cholecystitis grading schema has modest discriminatory power similar to the Tokyo Guidelines, but generally lower than the Parkland grade, and should be modified before widespread use. LEVEL OF EVIDENCE Diagnostic study, level IV.

Revision of the AAST grading scale for acute cholecystitis with comparison to physiologic measures of severity

“…Many of the grading systems, including the original and revised AAST grade, have demonstrated good capacity for predicting outcomes. These grading scales range from simple to complex however most include both anatomic, physiologic and comorbidity variables 8,9,18 . The advantage of the AAST grade is its predictive capacity while relying on only minimal physiologic criteria and no comorbidity data.…”

“…These grading scales range from simple to complex however most include both anatomic, physiologic and comorbidity variables. 8,9,18 The advantage of the AAST grade is its predictive capacity while relying on only minimal physiologic criteria and no comorbidity data. It also uses only objective data points that can be easily abstracted from an electronic record with respect to the clinical and imaging domains.…”

“…We have previously compared the American Association for the Surgery of Trauma (AAST) grading scale for acute cholecystitis with the Tokyo guidelines and the Parkland grade. 8 The AAST grade performed less well than the Parkland grade but similar to the Tokyo guidelines. This was at least partially driven by a lack of dispersion of patients across grades.…”

“…Collection of the patient data was thoroughly described in our prior article 8 . Briefly eight institutions prospectively collected data for all patients admitted with acute cholecystitis.…”

“…Understanding the severity of the cholecystitis is also valuable for informing patients, benchmarking hospital and surgeon performance and potentially determining reimbursement. We have previously compared the American Association for the Surgery of Trauma (AAST) grading scale for acute cholecystitis with the Tokyo guidelines and the Parkland grade 8 . The AAST grade performed less well than the Parkland grade but similar to the Tokyo guidelines.…”