Risk Factors and Nomogram for Pancreatic Stone Formation in Chronic Pancreatitis over a Long-Term Course: A Cohort of 2,153 Patients

Background: Pancreatic stones are pathognomonic of chronic pancreatitis (CP). This study aimed to determine the incidence, identify risk factors, and develop a nomogram for pancreatic stones in CP patients. Methods: Patients with CP admitted to our center from January 2000 to December 2013 were enrolled. Cumulative rates of pancreatic stones after the onset of CP and after the diagnosis of CP were calculated. Patients were randomly assigned, in a 2:1 ratio, to the training and validation cohort. Based on the training cohort, risk factors were identified through Cox proportional hazards regression model, and nomogram was developed. Internal and external validations were performed based on the training and validation cohort, respectively. Results: With a total of 2,153 CP patients, pancreatic stones were detected in 1,626 (75.5%) patients, with a median follow-up of 7.8 years. Age at the onset of CP, body mass index, smoking, diabetes mellitus, pancreatic pseudocyst, biliary stricture, severe acute pancreatitis, and type of pain were identified risk factors for pancreatic stones development. The nomogram with these 8 factors achieved good accuracy. Conclusions: The nomogram achieved an individualized prediction of pancreatic stones development in CP. It may help the management of pancreatic stones.