Post hoc validation of a tool that accurately predicts the outcome of endoscopic therapy in Bouveret syndrome

BACKGROUND: Bouveret syndrome is characterized by gallstone impaction in the upper gastrointestinal tract causing gastric outlet obstruction. In Bouveret syndrome, endoscopic gallstone removal can avert the need for surgery. However, in cases in which endoscopic therapy is unlikely to succeed, endoscopic attempts delay definitive treatment and compound patient risks. We previously developed a model that predicts endoscopic outcomes from data derived through a systematic review. This tool uses gallstone length, site of impaction, and the number of planned methods of lithotripsy to predict the likelihood of endoscopic success with an accuracy of 81.0%. This study aimed to evaluate our tool performance in an independent, non-training data set and assess endoscopic and surgical outcomes. METHODS: Systematic searches of the PubMed, Scopus, and Cochrane databases were performed for articles published between 16 April 2018 and 1 June 2021. The data reported after our previous study were harvested and inputted into the tool to evaluate their ability to accurately predict outcomes when compared with actual outcomes. RESULTS: Newly collated data in fields of interest showed no significant statistical differences compared with previous training data sets. Endoscopic therapy was successful in 41.9% of cases. Gallstones of ≤4 cm had a higher chance of successful endoscopic intervention (odds ratio 6.7, 95% confidence interval 1.7–25.8, P < 0.01). Complications of surgery were reported in 29.5%; there was one fatality reported. Post hoc evaluation of our predictive tool demonstrated an AUROC score of 0.80. CONCLUSIONS: We have demonstrated in an independent data set that the tool can be used to accurately predict outcomes of endoscopic therapy. Patients in whom endoscopic therapy is most likely to fail should be offered an early surgical opinion.