Bedside score predicting retained common bile duct stone in acute biliary pancreatitis

BACKGROUND: Retained common bile duct (CBD) stone after an acute episode of biliary pancreatitis is of paramount importance since stone extraction is mandatory. AIM: To generate a simple non-invasive score to predict the presence of CBD stone in patients with biliary pancreatitis. METHODS: We performed a retrospective study including patients with a diagnosis of biliary pancreatitis. One hundred and fifty-four patients were included. Thirty-three patients (21.5%) were diagnosed with CBD stone by endoscopic ultrasound (US). RESULTS: In univariate analysis, age (OR: 1.048, P = 0.0004), aspartate transaminase (OR: 1.002, P = 0.0015), alkaline phosphatase (OR: 1.005, P = 0.0005), gamma-glutamyl transferase (OR: 1.003, P = 0.0002) and CBD width by US (OR: 1.187, P = 0.0445) were associated with CBD stone. In multivariate analysis, three parameters were identified to predict CBD stone; age (OR: 1.062, P = 0.0005), gamma-glutamyl transferase level (OR: 1.003, P = 0.0003) and dilated CBD (OR: 3.685, P = 0.027), with area under the curve of 0.8433. We developed a diagnostic score that included the three significant parameters on multivariate analysis, with assignment of weights for each variable according to the co-efficient estimate. A score that ranges from 51.28 to 73.7 has a very high specificity (90%-100%) for CBD stones, while a low score that ranges from 9.16 to 41.04 has a high sensitivity (82%-100%). By performing internal validation, the negative predictive value of the low score group was 93%. CONCLUSION: We recommend incorporating this score as an aid for stratifying patients with acute biliary pancreatitis into low or high probability for the presence of CBD stone.