Acute Pancreatitis: Likelihood Ratios

Introduction: Pancreatitis represents acute inflammation of the pancreas, most commonly due to alcohol or gallstones. Several of the diagnostic tests below can help to distinguish the etiology.

Note that several formulas have been developed to predict those pts who are more likely to have a complicated course of pancreatitis, including Ranson and Glascow/Imrie criteria and the APACHE II scoring system.

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Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Acute abdominal pain	2.5%	J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
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The likelihood ratios of findings for Acute Pancreatitis are listed below. See the left navigation bar to change the display.

Good Positive and Negative Likelihood Ratios

Finding	+LR	-LR	Comments, Study
Elevated Serum Lipase Duplicate	100	0	>3x upper limit of normal. More than 2/3 of patients with acute pancreatitis with normal amylase will have elevated lipase. Lipase rises within 4-8 hours and remains elevated for 8-14 days. Note that lesser elevations of lipase in the context of nonspecific abdominal pain usually do not represent pancreatitis, with ~80% of patients having completely normal imaging (PMID 12522473). Also note that lipase may be elevated in other conditions such as hepatitis C, IBD, DKA, and renal failure (PMID 15653954). Study: Am J Gastroenterol. 2002 Jun;97(6):1309-18. PMID: 12094843
Elevated Serum Lipase Duplicate	100	0	Study: no study specified.
Urine Trypsinogen-2	12	0	by dipstick Study: Am J Gastroenterol. 2002 Jun;97(6):1309-18. PMID: 12094843
Immunoreactive Trypsinogen	5.7	0	(rarely used) Study: Am J Gastroenterol. 2002 Jun;97(6):1309-18. PMID: 12094843
Elevated Serum Amylase Duplicate	4.8	0.1	>300IU/ml Note that up to 32% of alcoholic pancreatitis patients may have normal serum amylase. In general, amylase is the first pancreatic enzyme to rise and also the first to fall in an episode of pancreatitis Study: Am J Gastroenterol. 2002 Jun;97(6):1309-18. PMID: 12094843
Lipase to Amylase Ratio	3.8	0.1	ratio > 2 - for alcoholic pancreatitis Study: Gastroenterology 1991 Nov;101(5):1361-6. PMID 1718808
Abdominal US	36	0.3	for gallstone pancreatitis Study: Pancreas. 1988;3(2):153-8. PMID: 3287369
Elevated Urine Pancreatic Amylase	23	0.3	A dipstick test with antibodies specific to pancratic amylase. Study: Scand J Clin Lab Invest. 1998 Dec;58(8):611-6. PMID: 10088197
Elevated Serum Amylase Duplicate	inf	0.4	>1000IU/ml Study: Am J Gastroenterol. 2002 Jun;97(6):1309-18. PMID: 12094843
Abdominal CT	inf	0.5	for gallstone pancreatitis Study: Pancreas. 1988;3(2):153-8. PMID: 3287369
Elevated ALT	12	0.5	>150 U/l - for gallstone pancreatitis Study: Am J Gastroenterol. 1994 Oct;89(10):1863-6. PMID: 7942684

Poorly Diagnostic Findings

Finding	+LR	-LR	Comments, Study
Anorexia	Sensitivity = 85%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Abdominal Rigidity	Sensitivity = 80%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Decreased Bowel Sounds	Sensitivity = 60%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
hearing loss	Sensitivity = 60%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Abdominal Tympany	Sensitivity = 60%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Pain radiating to Back	Sensitivity = 50%		The pain is often relieved by sitting up and bending forward. The pain is made worse by food. Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Guarding	Sensitivity = 50%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Shock	Sensitivity = 15%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Jaundice	Sensitivity = 15%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208
Hematemesis	Sensitivity = 10%		Study: J Hepatobiliary Pancreat Surg. 2006;13(1):25-32. PMID: 16463208