Pre-Operative Predictors of Concurrent Choledocholithiasis in Patients With Acute Calculus Cholecystitis: An External Validity Analysis.

ABSTRACT

Introduction Patients that are presented with acute calculus cholecystitis (AC) and elevated liver enzymes markers (LEM), often require evaluation for concurrent choledocholithiasis (CDL). Currently, evaluation guidelines follow the American Society of Gastroenterology Endoscopy (ASGE) recommendations. Objectives The aim of the study was to externally validate both ASGE and the Chisholm predictors in a community hospital patient cohort. Methods We conducted a retrospective study of patients who presented to Ascension Saint John hospital with AC and elevated LEM over a period of two years. Sensitivity (SEN), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV) were used to test the external validity of ASGE and Chisholm algorithms. Results A total of 132 patients' charts were reviewed, and 87 patients included. Chisholm predictors SEN, SP, PPV and NPV were 50%, 82%, 18%, and 95% respectively versus 100%, 19%, 8%, 100% for the ASGE predictors model. In the ASGE module, SP and PPV can be significantly improved to 60% and 13%, respectively, by changing a few risk categories including age and LEM range. Conclusions External validation of the Chisholm module in our patient cohort showed that it would lead to a low referral rate for unnecessary imaging and thus might be more cost-effective, especially when compared to current ASGE recommendations which would have a higher referral rate. On the other hand, current ASGE recommendations successively labeled all the patients with CDL, while the Chisholm module missed around 50 percent. We also observed that with the current ASGE module, the referral rate for further imaging and diagnostic tests can be possibly improved by adjusting a few of the predictors including the age and the abnormal liver transaminases range, but this observation is arbitrary and will need to be validated in a larger cohort study.