Validating a new grading scale for emergency general surgery diseases

The American Association for the Surgery of Trauma (AAST) recently developed a grading scale for measuring anatomic severity of emergency general surgery (EGS) diseases. Grades were developed by expert consensus and have not been validated. The study purpose was to measure inter-rater reliability of the grading scale using colonic diverticulitis and to measure the association between disease grade and patient outcomes.

All charts were reviewed and independently assigned AAST grades based on specific disease criteria. Inter-rater reliability was measured using a kappa coefficient. Multivariate regression models were used to determine the relationship between AAST disease grade and patient outcomes adjusted for age, comorbidities, and patient physiology.

Over 70% of patients demonstrated mild disease (grades I and II). No deaths were encountered. Inter-rater reliability for grade assignment was moderate (kappa coefficient, 0.43; 95% confidence interval, 0.31-0.56), with 67% concordance in grades. Compared to grade I, complications were similar in grade II but increased significantly with higher grades (grade III odds ratio [OR], 3.13 [1.32-7.41]; grade IV OR, 8.18 [2.09-32.0]; and grade V OR, 10.2 [2.68-38.90]). Compared to grade I, length of stay increased with higher grades (grade II incidence rate ratio [IRR], 1.30 [1.07-1.60]; grade III IRR, 2.4 [1.93-2.98]; grade IV IRR, 3.2 [2.27-4.60]; and grade V IRR, 2.6 [1.82-3.60]).

The EGS grading scale for diverticulitis demonstrated moderate inter-rater reliability. Higher grades were independently associated with complications and length of stay. The findings provide a positive validation that the EGS scale is easily used and effective.