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GENERAL CONSIDERATIONS IN ACUTE PANCREATITIS
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Recent U.S. estimates from the Nationwide Inpatient Sample report that acute pancreatitis is the most common inpatient principal gastrointestinal diagnosis. The incidence of acute pancreatitis also varies in different countries and depends on cause (e.g., alcohol, gallstones, metabolic factors, drugs [Table 341-1]). The annual incidence ranges from 13 to 45 cases per 100,000 persons. Acute pancreatitis results in >250,000 hospitalizations per year. The median length of hospital stay is 4 days, with a median hospital cost of $6096 and a mortality of 1%. The estimated cost annually approaches $2.6 billion. Hospitalization rates increase with age, which are 88% higher among blacks, and are higher among males than females. The age-adjusted rate of hospital discharges with an acute pancreatitis diagnosis increased 62% between 1988 and 2004. From 2000 to 2009, the rate increased 30%. Thus, acute pancreatitis is increasing and is a significant burden on health care costs and resource utilization.
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ETIOLOGY AND PATHOGENESIS IN ACUTE PANCREATITIS
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There are many causes of acute pancreatitis (Table 341-1), but the mechanisms by which these conditions trigger pancreatic inflammation have not been fully elucidated. Gallstones and alcohol account for 80–90% of the acute pancreatitis cases in the United States. Gallstones continue to be the leading cause of acute pancreatitis in most series (30–60%). The risk of acute pancreatitis in patients with at least one gallstone <5 mm in diameter is fourfold greater than that in patients with larger stones. Alcohol is the second most common cause, responsible for 15–30% of cases in the United States. The incidence of pancreatitis in alcoholics is surprisingly low (5/100,000), indicating that in addition to the amount of alcohol ingested, other factors affect a person’s susceptibility to pancreatic injury such as cigarette smoking. Acute pancreatitis occurs in 5–10% of patients following endoscopic retrograde cholangiopancreatography (ERCP). Use of a prophylactic pancreatic duct stent and rectal nonsteroidal anti-inflammatory drugs (NSAIDs, indomethicin) has been ...