a mortality of less than one percent, whereas patients with a score of five had a mortality rate of 22 percent. in the validation cohort, the bisap score had similar test performance characteristics for predicting mortality as the apache ii score. as is a problem with many of the other scoring systems, the bisap has not been validated for predicting outcomes such as length of hospital stay, need for icu care, or need for intervention. epidemiology in the united states, the annual incidence is 18 cases of acute pancreatitis per 100,000 population, and it accounts for 220,000 hospitalizations in the us. in a european cross-sectional study, incidence of acute pancreatitis increased from 12.4 to 15.9 per 100,000 annually from 1985 to 1995; however, mortality remained stable as a result of better outcomes. another study showed a lower incidence of 9.8 per 100,000 but a similar worsening trend (increasing from 4.9 in 1963–74) over time. in western countries, the most common cause is alcohol, accounting for 65 percent of acute pancreatitis cases in the us, 20 percent of cases in sweden, and 5 percent of those in the united kingdom. in eastern countries, gallstones are the most common cause of acute pancreatitis. the causes of acute pancreatitis also varies across age groups, with trauma and systemic disease (such as infection) being more common in children. mumps is a more common cause in adolescents and young adults than in other age groups.