Predicting and evaluation the severity in acute pancreatitis using a new modeling built on body mass index and intra-abdominal pressure.

•A new model based on intra-abdominal pressure and body mass index is built to predict the severity in acute pancreatitis.•The new model is more accurate than other scoring systems in prediction the severity of acute pancreatitis.•The new model is easy to be mastered and utilized; and is not difficult to collect the information of the two variables.