Imaging-independent model for predicting choledocholithiasis in acute biliary pancreatitis

Figure 1 Flowchart of patient selection. Screening of 601 patients with ICD-10 codes for biliary pancreatitis at LMU University Hospital (2005-2021), application of exclusion criteria, and derivation of the final cohort of 348 patients with acute biliary pancreatitis. ERCP: Endoscopic retrograde cholangiopancreatographies; CDL: Choledocholithiasis.

Figure 2 Variable importance. The importance of each variable included in the random forest model is estimated by the inverted mean minimal depth of each variable in the decision tree. GGT: Gamma-glutamyl transferase; AP: Alkaline phosphatase; CRP: C-reactive protein; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase.

Figure 3 Comparison of decision rules. A: Mosaic diagram in which each field’s size corresponds to the number of correct and false rule-in and rule-out classifications (i.e., the four cells of the respective contingency tables). False rule-outs in red signify missed CDL, and correct rule-outs in yellow correspond to true negatives for CDL; B: Two receiver operating characteristic (ROC) curves were plotted for the random forest model and the common bile duct diameter; C: ROC curve for our predictive model. CDL: Choledocholithiasis; AUC: Area under the curve; CI: Confidence interval; FPR: False positive rate; CBD: Common bile duct; GTE: Greater than or equal to.

Figure 4 Comparison of decision rules for microlithiasis and sludge. Model performances were computed for two subgroups. A: Patients with gallstones (n = 45); B: Patients with sludge and/or microlithiasis (n = 25). Two receiver operating characteristic curves were plotted for each subgroup for the random forest model, the common bile duct diameter and bilirubin. AUC: Area under the curve; CDL: Choledocholithiasis; CBD: Common bile duct; CI: Confidence interval; FPR: False positive rate.