Predicting severity of acute pancreatitis.

Severity stratification is a critical issue in acute pancreatitis that strongly influences diagnostic and therapeutic decision making. According to the widely used Atlanta classification, "severe" disease comprises various local and systemic complications that are associated with an increased risk of mortality. However, results from recent clinical studies indicate that these complications vary in their effect on outcome, and many are not necessarily life threatening on their own. Therefore, "severe," as defined by Atlanta, must be distinguished from "prognostic," aiming at nonsurvival. In the first week after disease onset, pancreatitis-related organ failure is the preferred variable for predicting severity and prognosis because it outweighs morphologic complications. Contrast-enhanced CT and MRI allow for accurate stratification of local severity beyond the first week after symptom onset. Among the biochemical markers, C-reactive protein is still the parameter of choice to assess attack severity, although prognostic estimation is not possible. Other markers, including pancreatic protease activation peptides, interleukins-6 and -8, and polymorphonuclear elastase are useful early indicators of severity. Procalcitonin is one of the most promising single markers for assessment of major complications and prognosis throughout the disease course.